Search results for "Pigs"
showing 10 items of 331 documents
Immunohistochemical evidence for the presence of peptides derived from proenkephalin, prodynorphin and proopiomelanocortin in the guinea pig pineal g…
1988
By using a plethora of region-specific antisera, this light microscopic immunohistochemical study revealed that derivatives from the three opioid precursors, i.e. proenkephalin, prodynorphin and proopiomelanocortin are differentially distributed in the pineal gland of guinea pig. Various molecular forms of immunoreactive opioid peptides derived from proenkephalin or prodynorphin were present in a minority of pinealocytes as well as in nerves. In contrast to this dual distribution pattern of opioid-active peptides, the opioid-inactive derivative from proopiomelanocortin, alpha-melanocyte stimulating hormone, was exclusively present in a large proportion of pinealocytes. A multiple and differ…
The effects of sex hormones, prolactin, and chorionic gonadotropin on pineal electrical activity in guinea pigs.
1981
Microelectrophoretic application of sex hormones onto pineal cells in guinea pigs has shown different responses in pregnant females as compared to males. In pregnant females estrone caused excitation in 74% of the cells tested, while progesterone and testosterone, prolactin, and HCG were inhibitory in a majority of the cells tested, while progesterone and testosterone, prolactin, and HCG were inhibitory in a majority of the cells. In contrast, in males estrone caused excitation of only 19% but inhibition of 37%. A smaller percentage of cells was inhibited by progesterone, while the predominant response to testosterone was excitation. These results suggest that the pineal gland may be under …
Antagonism of calcium by zinc in guinea-pig isolated taenia caeci and trachealis muscle
1989
1 In guinea-pig isolated taenia caeci and trachealis bathed in a K+-rich, Ca2+-free medium, CaCl2 (0.01-10 mM) produced a concentration-dependent contraction. Zn2+ (0.01-1 mM), Cd2+ (0.01-1 mM), verapamil (0.01-100 microM) and trifluoperazine (1-100 microM) were effective antagonists of CaCl2-induced responses. 2 Zn2+ and Cd2+ in concentrations from 0.01 to 1 mM were without effect on the tone of taenia and trachea in normal Tris solution. Conversely, Zn2+ and Cd2+, in concentrations of 1 mM, caused contraction of these tissues in a K+-rich, Ca2+-free medium. Zn2+ (1 mM)-induced contractions of taenia and trachea were completely inhibited by verapamil (10 microM). 3 In taenia and trachea sk…
New bronchodilators selected by molecular topology.
1998
Molecular topology has been applied to find new lead compounds with bronchodilator activity. Among the selected compounds stands out 3-(1H-tetrazol-5yl)-9H-thioxanthene-9 -one-10,10-dioxide, anthrarobin, 9-oxo-9H-thioxantene-3-carboxylic-10,10-dioxide acid, acenocoumarol and griseofulvin, with a percentage of relaxation, at 0.1 mM, of 91, 92, 85, 69, and 74%, respectively. Theophylline shows a correspondent value of 77% (Emax = 100% at 1 mM).
Effects of alkylxanthines on contractility of diaphragm fibres isolated from normal and sensitized guinea-pigs.
1993
Abstract This study investigates the effects of alkylxanthines on twitch tension generated by electrical stimulation (supramaximal pulses, 0·2 ms duration, 1 Hz) of diaphragm muscle fibres isolated from normal and actively-sensitized guinea-pigs. Caffeine, theophylline and theobromine increased, in a concentration-dependent manner (50–500 μm), twitch tension in normal and sensitized diaphragm. Caffeine (500 μm) enhanced contractility to a greater extent than theophylline or theobromine. Twitch potentiation by caffeine (500 μm) was significantly greater in sensitized diaphragm. Verapamil (0·1–100 μm) did not alter twitch contractions in the absence or presence of alkylxanthines in normal or …
The specificity of prostaglandin E2 (PGE2) in reducing coronary vascular resistance: A comparison with adenosine.
1978
Experiments were performed on the isolated, electrically driven guinea-pig heart, perfused at constant rate. All animals were pretreated with reserpine. Myocardial contractile force (MCF), coronary perfusion pressure (CPP) and myocardial oxygen consumption (QO2) were monitored continuously. Both adenosine (ADO) and PGE2 produced a concentration-dependent decrease in the CPP. The ED50 (50% of maximum response) was 2.1 +/- 0.6 X 10(-9)M for PGE2 but 40 +/- 7 X 10(-9)M for ADO (P less than 0.01) at 1.8 mM Ca(e). This coronary vasodilation was independent of the external Ca-concentration, which was varied between 0.55-9.0 mM. PGE2 had no effect on MCF or QO2 and the effect of ADO was only sligh…
The effect of S-(+)-boldine on the α1-adrenoceptor of the guinea-pig aorta
1996
1. The cardiovascular activity of S-(+)-boldine, an aporphine alkaloid structurally related to papaverine, was determined. The work includes functional studies on guinea-pig isolated aorta contracted with noradrenaline, caffeine, KCl or Ca2+, and on guinea-pig trachea contracted with acetylcholine or histamine. 2. S-(+)-boldine inhibited in a concentration-dependent manner the contractile response evoked by noradrenaline (10 microM) in guinea-pig aorta (IC50 = 1.4 +/- 0.2 microM) while the KCl depolarizing solution (60 mM)- or the Ca2+ (1 mM)-induced contractions were only partially affected by boldine up to 300 microM. In contrast, papaverine relaxed noradrenaline (NA), KCl or Ca2+ induced…
Cholinergic and GABAergic regulation of nitric oxide synthesis in the guinea pig ileum.
1999
Nitric oxide (NO) synthesis was examined in intact longitudinal muscle-myenteric plexus preparations of the guinea pig ileum by determining the formation of [3H]citrulline during incubation with [3H]arginine. Spontaneous [3H]citrulline production after 30 min was 80–90 dpm/mg, which constituted ∼1% of the tissue radioactivity. Electrical stimulation (10 Hz) led to a threefold increase in [3H]citrulline formation. Removal of calcium from the medium or addition of N G-nitro-l-arginine strongly inhibited both spontaneous and electrically induced production of [3H]citrulline. TTX reduced the electrically induced but not spontaneous [3H]citrulline formation. The electrically induced formation o…
Differentiation of calcium antagonists with respect to their effects in normal and skinned taenia caeci preparations
1987
Abstract In taenia preparations, depolarized by a K+-rich medium, Ca2+ caused contraction and cinnarizine (0.4–100 μM), trifluoperazine (2–100 μM) and verapamil (0.02–10 μM) caused concentration-dependent antagonism of Ca2+, displacing the Ca2+ log concentration-effect curve to the right and depressing the maximal response. Equieffective (IC75) antispasmogenic concentrations were selected. The antispasmogenic effects of verapamil were readily offset by removing the drug from the bathing fluid but those of the other drugs were not. The calcium antagonists (antispasmogenic IC75) were then tested for spasmolytic activity in tissues generating tension in response to the EC80 of Ca2+. Verapamil …
Effects of Ca2+ channel antagonists in guinea-pig normal and skinned gall bladder.
1993
CaCl2 (0.01-50 mM, in K(+)-depolarized tissues), KCl (0.1-100 mM) and acetylcholine (1 nM-10 mM) produced concentration-dependent contractions of guinea-pig isolated gall bladder. Nifedipine (1-100 microM), verapamil (1-100 microM), diltiazem (1-100 microM), cinnarizine (1-100 microM), and flunarizine (1-100 microM) each produced a concentration-related inhibition of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (50 mM)-induced contraction of depolarized gall bladder, was diltiazem (0.25 microM)or = verapamil (0.8 microM) approximately nifedipine (1.2 microM)cinnarizine (25 microM) approximately flunarizine …