Search results for "Norepinephrine"

Beta-adrenoceptor-mediated facilitation of endogenous noradrenaline release from rat isolated trachea.

1994

Overflow of endogenous noradrenaline from rat isolated trachea was evoked by electrical field stimulation (3 Hz, 540 pulses) in the presence of yohimbine, desipramine and tyrosine. Isoprenaline 100 nmol/l increased the evoked overflow of noradrenaline by about 65%. This effect was antagonized by propranolol (100 nmol/l) and the beta 2-selective adrenoceptor antagonist ICI 118,551 (100 nmol/l), but not by the beta 1-selective adrenoceptor antagonist CGP 20712 A (100 nmol/l). The beta 2-selective adrenoceptor agonist formoterol (1-100 nmol/l) also facilitated the evoked overflow of noradrenaline, but maximally by only about 25% at 10 nmol/l, i.e. formoterol behaved as a partial agonist at the…

Effects of exercise training on adrenergic and cholinergic responses of rabbit carotid artery

2013

Acute and Chronic Captopril, but Not Prazosin or Nifedipine, Normalize Alterations in Adrenergic Intracellular Ca2+ Handling Observed in the Mesenter…

2004

The effect of hypertension and acute (36-h) or chronic (from age 6 to 16 weeks) antihypertensive treatment with prazosin (2 mg kg(-1) per day), nifedipine (50 mg kg(-1) per day), or captopril (50 mg kg(-1) per day) on Ca2+ mobilization due to alpha1-adrenoceptor activation was analyzed in functional studies using arterial rings [four conductance/distributing vessels: aorta, main mesenteric, iliac, and tail arteries and two resistance vessels; first and second small mesenteric artery branches obtained from spontaneously hypertensive rats (SHR, 6 and 16 weeks old) and age-matched Wistar Kyoto rats (WKY)]. Maximal response to noradrenaline in the presence of extracellular Ca2+ is not affected …

Antagonism by SR 48692 of mechanical responses to neurotensin in rat intestine.

1996

Abstract 1. The effects of SR 48692 on neurotensin (NT)-induced mechanical responses were investigated in rat duodenum and proximal colon by use of isometric, isovolumic preparations. 2. SR 48692 inhibited the relaxant responses to NT in duodenal circular and longitudinal muscle. It also antagonized the NT-induced contractile effects in duodenal circular muscle and in proximal colon (both muscular layers). 3. From Schild analysis and pA2 value for SR 48692 was 8.2 in tissues where NT induced relaxant effects and 7.5 in tissues where NT induced contractile effects and the slope of the regression line was not significantly different from unity, indicating competitive antagonism. 4. SR 48692 d…

The influence of dopamine on hemodynamics, microcirculation and renal function in patients with hypnotic drug intoxication

1976

The effect of dopamine on hemodynamics (CO, AoPm, TPR, SV, SW, CVP, PAPm, PAEDP), microcirculation (MBF, PS-product) and renal function (VU, CKI, CNa, CK, Cosm, TcH2O) was studied in 8 patients with hypnotic drug poisoning. With increasing doses of dopamine, cardiac output and heart rate increased and the peripheral resistance decreased. An augmentation of stroke volume and left ventricular stroke work was observed in the low dose range only (200--400 mug/min). With increasing doses, central venous pressure as well as mean pulmonary artery pressure and enddiastolic pulmonary artery pressure decreased. No vasoconstriction was found in muscle tissue vessels even with large doses of dopamine. …

Effects of Norepinephrine and Cardiotrophin-1 on Phospholipase D Activity and Incorporation of Myristic Acid Into Phosphatidylcholine in Rat Heart

2004

The present study is part of a project on phospholipase D (PLD) in cardiac hypertrophy and analyzed effects on PLD activity of two growth stimuli, norepinephrine (NE) and cardiotrophin-1 (CT-1), in incubated rat heart. Phosphatidylcholine (PC) was labeled by 3H-myristic acid. PLD produced 3H-phosphatidylethanol (3H-PEth) from 3H-PC in the presence of ethanol and maintained a basal formation of 3H-PEth. Short-term and long-term exposure to NE for 2 or 13 h, respectively, enhanced the formation of 3H-PEth, which was blocked by prazosin. Long-term pretreatment with NE or CT-1 increased the incorporation of 3H-myristic acid into PC, which was blocked by atenolol. When the 3H-PEth formation was …

Direct and neuromodulatory effects of histamine on isolated goat cerebral arteries.

1992

1. The effects of histamine on isolated goat middle cerebral artery were examined using two experimental approaches: recording of isometric tension and measurement of [3H]-noradrenaline efflux. 2. Cumulative addition of histamine (10(-7)-3 x 10(-2)M) and 2-pyridylethylamine (2-PEA, 10(-6)-3 x 10(-2)M) produced concentration-dependent contractile responses. Preincubation with diphenhydramine (10(-7), 10(-6)M) or cimetidine (10(-7), 10(-6)M) competitively inhibited the histamine-induced contractile response. 3. Endothelium denudation enhanced the contractile effects of histamine. 4. Transmural electrical stimulation elicited contractions which were enhanced by histamine (10(-7)M), 2-PEA (10(-…

Failure of opioids to affect excitation and contraction in isolated ventricular heart muscle

1989

The opioid agonists morphine (selective for mu-receptors) and ethylketocyclazocine (selective for kappa-receptors), at concentrations evoking strong effects in neuronal structures, did not significantly affect the configuration of the intracellularly recorded action potential and the force of contraction in ventricular heart muscle isolated from guinea pigs, rabbits and man. These results suggest that any changes of heart functions in vivo in response to opioid-like drugs are probably not mediated postsynaptically at the myocardial cell membrane but rather presynaptically, influencing the release of noradrenaline and/or acetylcholine from the nerve terminals.

Different muscarine receptors mediate the prejunctional inhibition of [3H]-noradrenaline release in rat or guinea-pig iris and the contraction of the…

1989

To investigate the muscarine receptor type mediating inhibition of [3H]-noradrenaline release from the isolated rat and guinea-pig iris we have determined the potency of antimuscarinic drugs to antagonize the methacholine-induced inhibition of [3H]-noradrenaline overflow evoked by field stimulation (3 Hz, 2 min). The prejunctional apparent affinities were compared with those obtained for postjunctional muscarine receptors mediating the methacholine-induced contraction of the isolated rabbit iris sphincter muscle. Prejunctional apparent affinity constants of pirenzepine (6.67), himbacine (8.51), methoctramine (7.92), 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP, 8.00), hexahydro-d…

General therapeutic guidelines

2017

There are currently no methods available that have been proven to promote or accelerate regenerative processes in nerves. This lack often leads to disappointment for both patient and physician.