摘要:

Effects of sodium vanadate on various vascular smooth muscles of guinea pigs, rabbits, and Wistar Kyoto rats (WKY) were studied. Sodium vanadate of concentrations higher than 10-5 M induced contractions in the aortae of all animals. The contractile effects varied among vascular smooth muscles, and mesenteric arteries showed no or only weak contractile response to the drug, while aortae showed higher contractile responses. In the portal veins, potentiation of spontaneous contractions was observed by the application of sodium vanadate. These responses were not blocked by treatments with adrenergic blocking agents or indomethacin, indicating the direct action of the drug on vascular smooth muscles. Treatment with 4,4’-diisothiocyanostilbene-2,2’-disulfonic acid (DIDS) blocked completely the contractile effects of sodium vanadate, whereas it showed no effect on K-contractures. Partial depolarization of the membrane by elevations of K concentration potentiated sodium vanadate-induced contractions and minimized the variations of responses among preparations. In K-depolarized preparations, sodium vanadate often induced relaxation of preparations. The contractile effects of sodium vanadate were not blocked by treatment with ouabain, though ouabain also showed contractile actions in a number of preparations. It was suggested that vanadate acts directly on vascular smooth muscles and causes contractions without relation to the inhibition of NaK-ATPase. It may cause contractions inhibiting Ca-ATPase of sarcoplasmic reticulum and/or of cell membrane, and cause relaxation by inhibiting ATPase of contractile proteins. The variations of the responses may be explained by differences of membrane permeability to vanad

ISSN:1018-1172    

DOI:10.1159/000158628

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

Substance P, vasoactive intestinal polypeptide, somatostatin and neuropeptide Y-like immunoreactivity was studied by immunocytochemistry in the wall of the blood vessels of the small intestine of the cat, rat and guinea-pig. Immunoreactive nerve fibres were localized by means of the peroxidase-antiperoxidase (PAP) procedure, by use of antisera raised against these peptides. These neuropeptide-containing nerve fibres were widespread in association with the blood vessels and especially with the dense network of perivascular nerves supplying arterioles. At the ultrastructural level, immunoreactive nerve fibres were found very close to the basement membrane of the capillary walls. No immunoreactive nerve fibres were found in the wall of the veins. The anatomical findings of the present study are consistent with the proposal that several neuropeptides could function as neurotransmitters or neuromodulators in the control of blood flow in the small intestine.

ISSN:1018-1172    

DOI:10.1159/000158629

出版商:S. Karger AG    

年代:1986

数据来源: Karger

摘要:

We studied the effects of histamine on perfused rabbit middle cerebral arteries in vitro. Intact and endothelium-denuded preparations were compared. Histamine caused concentration-dependent constrictions in intact vessels which were competitively inhibited by an H1 receptor antagonist. This constriction was potentiated by either H2-receptor blockade or endothelium denudation. The greatest potentiation was observed with intraluminal as opposed to extraluminal administration. The H1 receptor agonist pyridylethylamine induced similar concentration-dependent constriction in intact and denuded preparations. After pre-constriction, histamine, in the presence of an H1 receptor antagonist, dilated intact vessels to a maximum of 45.1 %, and endothelium-denuded vessels to a maximum of 22% (p < 0.02). We conclude that rabbit middle cerebral arteries possess H1 constrictory and H2 dilatory receptors, and that many of the H2 dilatory receptors are situated on the endothelial cells.

ISSN:1018-1172    

DOI:10.1159/000158632

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158633

出版商:S. Karger AG    

年代:1986

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158634

出版商:S. Karger AG    

年代:1986

数据来源: Karger