0000000000039771
AUTHOR
Pascual Medina
showing 30 related works from this author
Aspirin and COX-2 Inhibitor Nimesulide Potentiate Adrenergic Contractions of Human Gastroepiploic Artery
2007
Background The aim of the present study was to evaluate the intervention of COX-1- and COX-2-derived prostaglandins in the responses of human gastroepiploic artery to sympathetic stimulation and norepinephrine. Methods Rings of human gastroepiploic artery were obtained from 45 patients (26 men and 19 women) undergoing gastrectomy. The rings were suspended in organ baths for isometric recording of tension. We studied the responses to electrical field stimulation, norepinephrine, and acetylcholine, in the absence and presence of COX-1 or COX-2 inhibition. Results The COX-1 and COX-2 inhibitor aspirin at high concentrations (10 −6 to 10 −5 mol/L) and the COX-2 inhibitor nimesulide (10 −6 mol/L…
Plasma concentrations of nitric oxide and asymmetric dimethylarginine in human alcoholic cirrhosis.
2004
The liver plays a prominent role in the metabolism of asymmetric dimethyl-l-arginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthase. This study was designed to determine whether plasma levels of ADMA and NO production are altered in patients with compensated and decompensated alcoholic cirrhosis.Plasma levels of l-arginine, ADMA, symmetric dimethylarginine (SDMA) and NO (nitrite plus nitrate, NOx) were measured in nine patients with compensated alcoholic cirrhosis (Child-Pugh A) and 11 patients with advanced cirrhosis (Child-Pugh B-C). Seven healthy volunteers served as controls.ADMA and NOx concentrations in decompensated cirrhosis were higher than in the compensated group a…
Effects of sildenafil on human penile blood vessels.
2000
Abstract Objectives. To investigate the effects of sildenafil on human penile blood vessels and evaluate the interaction of sildenafil with neurogenic-mediated responses. Sildenafil is currently used in the treatment of erectile dysfunction. Methods. Penile dorsal arteries and deep dorsal veins were obtained from 14 multiorgan donors. Vascular rings were suspended in organ bath chambers, and the isometric tension was recorded. We then studied the effects of sildenafil on precontracted vessels and the neurogenic (noradrenergic and nitrergic) responses. Results. Sildenafil (10 −9 to 3 × 10 −6 M) caused concentration-dependent relaxation and amplified the relaxation induced by sodium nitroprus…
Modulation of adrenergic contraction of dog pulmonary arteries by nitric oxide and prostacyclin.
1999
Abstract The aim of this work was to investigate the influence of endothelium-derived nitric oxide and prostaglandins on the contractile responses of isolated dog pulmonary arteries to electrical field stimulation and noradrenaline. Electrical field stimulation (1–8 Hz, 20 v, 0.25 ms duration, for 30 s) produced frequency-dependent contractions that were abolished by tetrodotoxin, guanethidine and, prazosin (all at 10−6 M). Noradrenaline induced concentration-dependent contractions with an EC50 of 1.85 × 10−6 M. The increases in tension induced by electrical stimulation and noradrenaline were of greater magnitude in arteries denuded of endothelium. In segments with endothelium, NG-nitro- l …
Contractile effects of arginine analogues on human internal thoracic and radial arteries
2000
Abstract Objectives: Plasma levels of endogenous guanidino-substituted analogues of L -arginine are increased in various pathologic conditions. In the present study we determined the effects of some of these compounds on basal and stimulated release of nitric oxide in human internal thoracic and radial arteries. Methods: Rings of human internal thoracic and radial arteries were obtained from 16 multiorgan donors. The rings were suspended in organ baths for isometric recording of tension. Results: N G -monomethyl L -arginine (10 –6 to 10 –3 mol/L) and N G ,N G -dimethyl L -arginine (10 –6 to 10 –3 mol/L) caused concentration- and endothelium-dependent contractions. Maximal force of contracti…
Basal release of nitric oxide in the mesenteric artery in portal hypertension and cirrhosis: Role of dimethylarginine dimethylaminohydrolase
2013
Background and Aim Increased basal release of nitric oxide (NO) in the splanchnic circulation contributes to elevated plasma levels of NO observed in decompensated cirrhosis. We evaluated in rat mesenteric arteries whether the differences in basal release of NO, revealed by asymmetric dimethylarginine (ADMA)- and NG-nitro-L-arginine methyl ester (L-NAME)-induced contractions, were associated with changes in messenger RNA (mRNA) expression of endothelial NO synthase (eNOS) and dimethylarginine dimethylaminohydrolases (DDAHs). Methods Rat small mesenteric arteries from 14 Sham-control, from 14 with partial portal vein ligation (PPVL), and from 14 with bile duct excision (BDE)-induced cirrhosi…
Arginine Vasopressin Enhances Sympathetic Constriction Through the V 1 Vasopressin Receptor in Human Saphenous Vein
1998
Background —Arginine vasopressin (AVP) not only acts directly on blood vessels through V 1 receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vivo and in vitro. The aim of the present study was to investigate whether AVP can contribute to an abnormal adrenergic constrictor response of human saphenous veins. Methods and Results —Saphenous vein rings were obtained from 32 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. AVP (3×10 −9 mol/L) enhanced the contractions elicited by electrical field stimulation at 1, 2, and 4 Hz (by 80%, 70%, and 60%, respectiv…
Neurogenic contraction and relaxation of human penile deep dorsal vein
1998
The aim of the present study was to characterize neurogenic and pharmacological responses of human penile deep dorsal vein and to determine whether the responses are mediated by nitric oxide from neural or endothelial origin. Ring segments of human penile deep dorsal vein were obtained from 22 multiorgan donors during procurement of organs for transplantation. The rings were suspended in organ bath chambers for isometric recording of tension. We then studied the contractile and relaxant responses to electrical field stimulation and to vasoactive agents. Electrical field stimulation (0.5–2 Hz) and noradrenaline (3×10−10–3×10−5M) caused frequency- and concentration-dependent contractions that…
Inhibition of nitric oxide activity by arginine analogs in human renal arteries
2001
Abstract Background: Plasma levels of endogenous guanidine compounds are increased in various pathologic conditions, including chronic renal failure. In the present study we tested the effects of some of these compounds on basal and stimulated nitric oxide activity in human renal arteries. Methods: Rings from human renal arteries were obtained from 22 patients undergoing nephrectomy. The rings were suspended in organ baths for isometric recording of tension. We then studied the effects of N G -monomethyl- l -arginine (L-NMMA), N G , N G -dimethyl- l -arginine (asymmetrical dimethylarginine [ADMA]), aminoguanidine (AG), and methylguanidine (MG) on artery rings under basal and stimulated cond…
Inhibition of neuroeffector transmission in human vas deferens by sildenafil
2000
Sildenafil (0.1 - 30 microM), a cyclic GMP phosphodiesterase 5 (PDE 5) inhibitor, induced inhibition of electrically evoked contractions of ring segments of human vas deferens from 34 vasectomies. Zaprinast (0.1 - 100 microM), another PDE 5 inhibitor, and the nitric oxide (NO) donor sodium nitroprusside (SNP) (0.1 - 100 microM) had no effect on neurogenic contractions. The inhibition induced by sildenafil was not modified by the inhibitor of guanylate cyclase 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) (1 - 30 microM) but it was abolished by the K(+) channel blockers tetraethylammonium (TEA, 1 mM), iberiotoxin (0.1 microM) and charybdotoxin (0.1 microM). Sildenafil, zaprinast and SNP…
Relaxation and cyclic GMP levels in response to sildenafil in human pulmonary arteries from donors.
2005
We measured cyclic GMP formation and relaxation response to sildenafil given either alone or in combination with sodium nitroprusside (SNP) in pulmonary arteries obtained from 13 multi-organ donors. Sildenafil (10(-9)-10(-4) M) caused concentration-dependent relaxations and amplified the relaxation induced by SNP. Relaxation was unaffected by endothelium removal or by pre-treatment with the inhibitor of nitric oxide synthase L-NMMA (10(-4) M). SNP (10(-7) M) caused elevation of cyclic GMP levels that was potentiated by sildenafil (10(-6) M). Thus, the enhancement of SNP-induced relaxation by sildenafil is mainly due to an increase in cyclic GMP accumulation.
Effects of aspirin, nimesulide, and SC-560 on vasopressin-induced contraction of human gastroepiploic artery and saphenous vein.
2007
Objective: The present experiments were designed to evaluate differences in the effects of cyclooxygenase (COX)-1 and COX-2 inhibition on contractile responses of human gastroepiploic artery and saphenous vein elicited by vasopressin. Design: Laboratory investigation. Setting: University laboratory. Subjects: Rings of human gastroepiploic artery were obtained from 32 patients undergoing gastrectomy, and rings of saphenous vein were obtained from 30 patients undergoing coronary artery bypass surgery. Interventions: The rings were suspended in organ baths for isometric recording of tension. We studied the responses to vasopressin in the absence and in the presence of either the vasopressin V …
Plasma concentration of asymmetric dimethylarginine, an endogenous inhibitor of nitric oxide synthase, is elevated in hyperthyroid patients.
2002
Cardiovascular manifestations are frequent findings in patients with thyroid hormone disorders. Nitric oxide (NO) plays a key role in vascular, endothelial-mediated relaxation. NO is synthesized from L-arginine by NO synthase, an enzyme inhibited by endogenous compounds, mainly asymmetric dimethylarginine [asymmetric N(G),N(G)-dimethyl-L-arginine (ADMA)]. The aim of our work was to investigate whether plasma L-arginine and dimethylarginine concentrations and NO production are altered in hypo- and hyperthyroid patients, compared with control subjects. L-arginine, ADMA and symmetric dimethylarginine were analyzed by HPLC. NO was measured as plasma nitrite plus nitrate (NO(x)) concentration by…
Endothelin-1-induced potentiation of adrenergic responses in the rabbit pulmonary artery: role of thromboxane A(2).
2001
Abstract To examine whether low concentrations of endothelin-1 potentiate the vasocontrictor response to adrenergic stimulation, we recorded the isometric response of rings of rabbit pulmonary artery to electrical stimulation and noradrenaline. Endothelin-1 (10 −10 M) potentiated the contractions induced by electrical stimulation and noradrenaline. The endothelin ET B receptor antagonist (2,6-dimethylpiperidinecarbonyl-γ-methyl-Leu- N in -[Methoxycarbonyl]- d -Trp- d -Nle) (BQ-788, 10 −6 M), but not the endothelin ET A receptor antagonist cyclo( d -Asp-Pro- d -Val-Leu- d -TRP) (BQ-123, 10 −6 M), inhibited the potentiating effects of endothelin-1. Pretreatment with the cyclooxygenase inhibit…
Aging Negatively Affects Estrogens-Mediated Effects on Nitric Oxide Bioavailability by Shifting ERα/ERβ Balance in Female Mice
2011
AIMS: Aging is among the major causes for the lack of cardiovascular protection by estrogen (E2) during postmenopause. Our study aims to determine the mechanisms whereby aging changes E2 effects on nitric oxide (NO) production in a mouse model of accelerated senescence (SAM). METHODS AND RESULTS: Although we found no differences on NO production in females SAM prone (SAMP, aged) compared to SAM resistant (SAMR, young), by either DAF-2 fluorescence or plasmatic nitrite/nitrate (NO2/NO3), in both cases, E2 treatment increased NO production in SAMR but had no effect in SAMP. Those results are in agreement with changes of eNOS protein and gene expression. E2 up-regulated eNOS expression in SAMR…
Influence of Endothelial Nitric Oxide on Adrenergic Contractile Responses of Human Cerebral Arteries
1996
The present study was designed to investigate the influence of the endothelium and that of the L-arginine pathway on the contractile responses of isolated human cerebral arteries to electrical field stimulation (EFS) and norepinephrine. Rings of human middle cerebral artery were obtained during autopsy of 19 patients who had died 3–8 h before. EFS (1–8 Hz) induced frequency-dependent contractions that were abolished by tetrodotoxin, prazosin, and guanethidine (all at 10-6 M). The increases in tension were of greater magnitude in arteries denuded of endothelium. NG-monomethyl L-arginine (L-NMMA 10-4 M) potentiated the contractile response to EFS in artery rings with endothelium but did not …
Endothelium-dependent relaxation of human saphenous veins in response to vasopressin and desmopressin
1997
Purpose: The goal of this study was to determine the effects of vasopressin and the selective V 2 -receptor agonist desmopressin on human saphenous veins, with special emphasis on endothelium-mediated responses. Methods: Human saphenous vein segments were obtained from 35 patients undergoing coronary bypass surgery. Paired segments, one normal and the other deendothelized by gentle rubbing, were mounted for isometric recording of tension in organ baths. Concentration-response curves to vasopressin and desmopressin were determined in the presence and in the absence of either the V,-receptor antagonist d(CH 2 ) 5 Tyr(Me)AVP (10 −6 mol/L), the V 1 -V 2 receptor antagonist desGly-d(CH 2 ) 5 D-T…
Potentiation by vasopressin of adrenergic vasoconstriction in the rat isolated mesenteric artery
1997
1. The aim of the present study was to investigate in rat mesenteric artery rings whether low concentrations of vasopressin could modify the contractile responses to noradrenaline and electrical stimulation of perivascular nerves. 2. Vasopressin (10[10]-10[-7] M) caused concentration-dependent contractions (pD2 = 8.36+/-0.09). The V1-receptor antagonist d(CH2)5Tyr(Me)AVP (10[-9]-10[-8] M) produced parallel rightward shifts of the control curve for vasopressin. Schild analysis yielded a pA2 value of 9.83 with a slope of 1.10+/-0.14. 3. Vasopressin (3 x 10[-10] and 10[-9] M) caused concentration-dependent potentiation of the contractions elicited by electrical stimulation (2-8 Hz; 0.2 ms dura…
Relaxation and cGMP formation in response to sildenafil and sodium nitroprusside in saphenous veins from normotensive and hypertensive patients1
2002
Abstract Background This study was designed to measure cyclic guanosine 3′5′ monophosphate (cGMP) formation and relaxation response to sildenafil given either alone or in combination with sodium nitroprusside in saphenous veins obtained from normotensive and hypertensive patients. Methods Saphenous vein rings were obtained from 13 hypertensive and nine normotensive patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. The effect of sildenafil on sodium nitroprusside-induced cGMP formation was also assessed. Results Sildenafil (10 nmol/L to 100 μmol/L) and sodium nitroprusside (0.01 to 100 nmol/L) caused c…
Enhancement by vasopressin of adrenergic responses in human mesenteric arteries.
1997
Vasopressin not only acts directly on blood vessels through V1-receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vitro and in vivo. The aim of the present study was to investigate whether subpressor concentrations of vasopressin could modify the constrictor responses to norepinephrine and electrical stimulation of the perivascular nerves in human mesenteric arteries. Human mesenteric artery rings (3-3.5 mm long, 0.8-1.2 mm OD) were obtained from 38 patients undergoing abdominal operations. The arterial rings were suspended in organ bath chambers for isometric recording of tension. Vasopressin (3 x 10(-11) M) enhanced the contractions elicited…
Effects of vasopressin on human renal arteries
1996
The effects of vasopressin were studied in isolated rings from branches (2-3 mm in external diameter) of human renal arteries obtained from 18 patients undergoing nephrectomy for non-obstructive neoplasia. In arterial rings under resting tension, vasopressin produced concentration-dependent and endothelium-independent contractions with an EC 50 of 9.1 x 10 -10 mol L -1 . The vasopressin V 1 receptor antagonist d(CH 2 ) 5 Tyr(Me)AVP (10 -6 mol L -1 ) displaced the control curve to vasopressin 564-fold to the right in a parallel manner. In precontracted arterial rings and previously treated with the V 1 antagonist (10 -6 mol L -1 ) vasopressin caused endothelium-independent relaxation. The re…
Influence of endothelial nitric oxide on neurogenic contraction of human pulmonary arteries.
1995
The present study was designed to investigate the contribution of the endothelium and that of the L-arginine pathway on the contractile responses of isolated human pulmonary arteries to electrical field stimulation (EFS) and noradrenaline. Isometric tension was measured in artery rings obtained from portions of human lung after thoracic surgery for removal of lung carcinoma (18 patients). Electrical field stimulation (EFS) induced frequency-dependent contractions of isolated human pulmonary arteries which were abolished by tetrodotoxin, guanethidine and prazosin (all at 10(-6) M). The increases in tension were of greater magnitude in arteries denuded of endothelium. NG-nitro-L-arginine meth…
Accumulation of Symmetric Dimethylarginine in Hepatorenal Syndrome
2005
In patients with cirrhosis, nitric oxide (NO), asymmetric dimethylarginine (ADMA), and possibly symmetric dimethylarginine (SDMA) have been linked to the severity of the disease. We investigated whether plasma levels of dimethylarginines and NO are elevated in patients with hepatorenal syndrome (HRS), compared with patients with cirrhosis without renal failure (no-HRS). Plasma levels of NO, ADMA, SDMA, and l-arginine were measured in 11 patients with HRS, seven patients with no-HRS, and six healthy volunteers. SDMA concentration in HRS was higher than in no-HRS and healthy subjects (1.47 ± 0.25 vs. 0.38 ± 0.06 and 0.29 ± 0.04 μM, respectively; P < 0.05). ADMA and NOx concentrations were…
Female Vascular Senescence
2012
Long before the existence of cardiovascular imaging, Sir William Osler axiom that “man is as old as his arteries”. Followed by several physicians for decades, this aphorism has been widely confirmed by studies demonstrating that risk factors for cardiovascular disease increase as we age (Cooper et al., 1994; Lakatta & Levy, 2003). Nevertheless, a flaw in this statement is the generalization that men and women age similarly. Much data from clinical and basic research have established that vascular aging in women does not follow the same chronology as in men (Shaw et al., 2006; Pereira et al., 2010; Takenouchi et al., 2009). If known risk factors that influence cardiovascular aging are exclud…
Effects of asymmetric dimethylarginine on renal arteries in portal hypertension and cirrhosis
2016
AIM. To evaluate the effects of asymmetric dimethylarginine (ADMA) in renal arteries from portal hypertensive and cirrhotic rats. METHODS. Rat renal arteries from Sham (n = 15), pre-hepatic portal hypertension (PPVL; n = 15) and bile duct ligation and excision-induced cirrhosis (BDL; n = 15) were precontracted with norepinephrine, and additional contractions were induced with ADMA (10-6-10-3 mol/L), an endogenous inhibitor of nitric oxide (NO) synthase. Concentration-response curves to acetylcholine (1 × 10-9-3 × 10-6 mol/L) were determined in precontracted renal artery segments with norepinephrine in the absence and in the presence of ADMA. Kidneys were collected to determine the protein e…
Relaxation of human isolated mesenteric arteries by vasopressin and desmopressin.
1994
1. The effects of vasopressin and deamino-8-D-arginine vasopressin (DDAVP, desmopressin) were studied in artery rings (0.8-1 mm in external diameter) obtained from portions of human omentum during the course of abdominal operations (27 patients). 2. In arterial rings under resting tension, vasopressin produced concentration-dependent, endothelium-independent contractions with an EC50 of 0.59 +/- 0.12 nM. The V1 antagonist d(CH2)5Tyr(Me)AVP (1 microM) and the mixed V1-V2 antagonist desGly-d(CH2)5D-Tyr(Et)ValAVP (0.01 microM) displaced the control curve to vasopressin to the right in a parallel manner without differences in the maximal responses. In the presence of indomethacin (1 microM) the…
Contractile hyporesponsiveness to norepinephrine of forearm veins in chronic renal failure.
2006
Background We recently reported that endothelium-dependent relaxation is impaired in forearm veins from patients with chronic renal failure. However, assessment of responses to norepinephrine remains controversial. We examined the contractile response to norepinephrine in forearm veins from patients on chronic hemodialysis and the role of nitric oxide (NO), prostanoids, and Ca 2+ -activated K + channels in this response. Methods Isometric contraction curves were obtained in rings of forearm vein from 21 dialyzed patients and 12 multiorgan donors in response to norepinephrine (1 nmol/L to 10 μmol/L) or KCl (5 to 100 mmol/L). Results Veins from uremic patients were markedly less responsive to…
Increased responsiveness of human pulmonary arteries in patients with positive bronchodilator response.
1996
Abstract 1. The effects of noradrenaline, endothelin-1, acetylcholine and sodium nitroprusside were studied in isolated pulmonary arteries obtained from 14 patients undergoing lobectomy for lung carcinoma. Seven patients had shown increased response to a bronchodilator test prior to operation. In the remaining patients (control) the bronchodilator test was negative. 2. Artery rings from patients with a positive bronchodilator response showed greater contraction to noradrenaline (pD2 = 6.44 +/- 0.1; Emax = 93 +/- 9% of response to 100 mM KCl) and endothelin-1 (pD2 = 8.92 +/- 0.1; Emax = 130 +/- 16%) than the rings from control patients (pD2 = 6.04 +/- 0.08; Emax = 56 +/- 8% for noradrenaline…
Endothelium-dependent responses in human isolated thyroid arteries from donors
2004
The functional properties of the endothelium of human thyroid arteries remain unexplored. We investigated the intervention of nitric oxide (NO), prostacyclin (PGI(2)) and endothelium-derived hyperpolarizing factor (EDHF) in the responses to acetylcholine and noradrenaline in isolated thyroid arteries obtained from multi-organ donors. Artery rings were suspended in organ baths for isometric recording of tension. The contribution of NO, PGI(2) and EDHF to endothelium-dependent relaxation was determined by the inhibitory effects of N(G)-monomethyl-L-arginine (L-NMMA), indomethacin, and K(+) channel inhibitors respectively. Acetylcholine induced concentration-dependent relaxation; this effect w…
Comparative effects of dilator drugs on human penile dorsal artery and deep dorsal vein
1998
The present study was designed to characterize the response of human penile dorsal artery and deep dorsal vein to dilator drugs used in the diagnosis and treatment of erectile dysfunction with special emphasis on the effects on sympathetic neurotransmission. Ring segments of penile dorsal artery and deep dorsal vein were obtained from 20 multi-organ donors during procurement of organs for transplantation. The rings (3 ;mm long) were suspended in organ bath chambers for isometric recording of tension. We then studied the relaxant responses to prostaglandin E1 (PGE1), vasoactive intestinal peptide (VIP), papaverine (PV), sodium nitroprusside (SNP) and linsidomine chlorhydrate (SIN-1), and ana…