摘要:

The effects of angiotensin I (AI) and angiotensin II (AII) on ring segments of femoral arteries from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) were studied. AI and AII elicited significantly greater direct contractile response in arteries from SHR than those from WKY. These peptides also potentiated the contractile response to transmural adrenergic nerve stimulation (TNS) in both preparations, but to a greater extent in those of WKY than SHR, without potentiating the contractile response to exogenous norepinephrine (NE). The potentiation of the TNS response and direct contraction caused by AI were markedly attenuated by captopril, an AI-converting enzyme inhibitor. Destruction of endothelium failed to alter the contractile response to AI in both WKY and SHR but augmented that to AII in WKY. Isoproterenol and salbutamol produced significant potentiation of TNS response only in arteries of SHR. Yohimbine and prostaglandin F2α potentiated TNS response to a similar extent in arteries of WKY and SHR. These results suggest that AII locally generated from AI can act postsynaptically to cause contraction and presynaptically to promote adrenergic neurotransmission in the isolated rat femoral artery. The AI to AII conversion appears to take place mainly at sites other than endothelial cells. The postsynaptic effect of AII is greater in SHR than WKY, but its presynaptic effect is diminished in SHR unlike some other agents which facilitate adrenergic neurotransmission, and unlike that in mesenteric arteries of SHR

ISSN:1018-1172    

DOI:10.1159/000158666

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Microvascular endothelial cell cultures have been established from mouse lung, liver, brain, heart, placenta, kidney, urinary bladder, mammary gland, ovary and epididymal fat pad. In addition, large vessel endothelial cells have been obtained from the mouse aorta and thoracic duct. The heterogeneity of these cells has been shown by flow cytometric determination of angiotensin-converting enzyme, by differential presence of the acetyl low density lipoprotein receptor, by the variable expression of cell surface antigens, and by differential binding of various plant lectins. The endothelial cell lines we have developed provide the means to examine in the mouse, long a key species for biomedical research, a wide range of biological functions and properties of the vascular endothelium.

ISSN:1018-1172    

DOI:10.1159/000158667

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Thromboxane A2 (TxA2), leukotriene C4 (LTC4), leukotriene D4 (LTD4), and platelet-activating factor (PAF) are novel lipids which exert a variety of biological actions. TxA2, LTC4 and LTD4 have been shown to induce direct vasoconstriction in several species, while PAF contracts isolated guinea pig ileum and lung parenchyma. We studied the direct vasoconstricting activities of these lipid mediators in isolated cat renal, superior mesenteric and coronary arteries. The TxA2 analog 9, 11-methanoepoxy PGH2 (U-46619) constricted both perfused and helical strips, with the renal and mesenteric arteries being 4 times more responsive than the coronary arteries. LTC4 and LTD4 constricted coronary arteries to a significantly greater extent than renal and superior mesenteric arteries in both perfused arteries and helical strips. Furthermore, PAF failed to contract any of the perfused arteries or helical strips at concentrations from 1 ng to 20 µg. TxA2 was a potent vasoconstrictor in all the vessels studied, suggesting a role for this substance as a vasoactive mediator in ischemia and shock. The coronary arteries were more responsive to the leukotrienes than the mesenteric and renal arteries, suggesting that the leukotrienes may play an important role in myocardial ischemia. Moreover, both thromboxane and leukotriene effects were blocked in all preparations by specific receptor antagonists. While the biological effects of PAF are still poorly understood, PAF does not directly vasoconstrict large arteries of the feline renal, superior mesenteric or coronary vasculatures

ISSN:1018-1172    

DOI:10.1159/000158668

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

The effect of vasoactive agents on the spontaneous contractions of the initial lymphatics of the bat’s wing was investigated. Initial lymphatic contractile frequency and pulsatile pressure were measured with the servo-null micropressure system. Norepinephrine, phenylepinephrine, isoproterenol, acetylcholine, histamine, serotonin, bradykinin, prostaglandin F2a, prostaglandin E2, indomethacin and ibuprofen were delivered to the immediate vicinity of the initial lymphatic by microinjection or iontophoresis. Only bradykinin produced changes in initial lymphatic contractions which were significantly different from control. The response to bradykinin was characterized by an increase in the frequency, strength or duration of the contractio

ISSN:1018-1172    

DOI:10.1159/000158669

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

We studied the functional effects of vasoactive intestinal peptide (VIP) and the structurally related peptide histidine isoleucine (PHI) in segments of bovine and human intrapulmonary artery. In both species, VIP caused nearly complete relaxation of precontracted vessel segments. The EC50 was 1.3 ± 0.3 × 10–9 M (mean ± SD) in bovine and 3.4 ± 0.4 × 10–9 M in human pulmonary artery. The response to VIP was not endothelium-dependent and it was not affected by either adrenergic and cholinergic blockade or by cyclooxygenase inhibition. PHI also relaxed human and bovine vessels but this related peptide was significantly less effective than VIP. We conclude that VIP is a potent inhibitor of bovine and human pulmonary artery, which appears to act directly on vascular smooth muscle. These data support the concept that VIP may be a neurotransmitter which modulates pulmonary artery tone in both man

ISSN:1018-1172    

DOI:10.1159/000158670

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

A whole mounted model for the study of smooth muscle mechanics is described which uses cylindrical sections of middle cerebral artery (MCA). One- to 2-cm sections of artery were cannulated, pressurized and perfused. Changes in the outer diameter of the artery were detected using an infrared photoelectric diameter gauge. MCA displayed spontaneous rhythmic contractions, which were initiated and sensitive to changing intraluminal pressure. Rhythmic activity was dependent upon the presence of Ca2+ in the bath, but not affected by phentolamine. Increasing pressure significantly reduced high (50, 70 and 125 mM) potassium-induced contractions, but not drug (serotonin, norepinephrine, histamine) induced contractions. The intraluminal surface of the MCA was significantly more sensitive to serotonin than the extraluminal surface. The above contractile responses are discussed in light of the advantages of this model over helical or ring preparations.

ISSN:1018-1172    

DOI:10.1159/000158671

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

We have investigated the changes in the responses to noradrenaline of isolated tail arteries of spontaneously hypertensive (SHR) and renovascular hypertensive rats (Wistar-Kyoto: two-kidney, one-clip model, WKY:2K1C) compared with normotensive (Wistar-Kyoto, WKY) rats. Renovascular hypertension was induced by 4 weeks’ unilateral renal artery clipping. Arteries were vasoconstricted with exogenous noradrenaline, electrical field stimulation or high potassium. The effects of the latter two stimuli were abolished by reserpine and so were presumably dependent on the presence of endogenous noradrenaline. In the SHR the maximal vasoconstriction produced by all three stimuli was greater than in WKY. Dose-response curves were steeper and there was no change in threshold. Vascular mass was greater. We interpret these results as showing an increase in vascular reactivity in the SHR caused by structural adaptation. The WKY:2K1C responses to noradrenaline could also be explained in terms of structural adaptation but there was no increase in vascular mass. Sensitivity to potassium and electrical stimulation was decreased, suggesting a defect in vascular neurotransmission. This was supported by the observations of a decreased arterial noradrenaline content and of decreased sensitivity to cocain

ISSN:1018-1172    

DOI:10.1159/000158672

出版商:S. Karger AG    

年代:1987

数据来源: Karger

摘要:

Detailed measurements of vessel lengths and diameters from the coronary network of the human heart are presented. To allow accurate definition of length and diameter, the measurements were made in terms of vessel segments rather than whole vessels. A vessel segment was defined to be the interval between two consecutive branching sites. The results provide the first quantitative description of the coronary network. The new concept of vessel segment and the method of analysis are proposed as a means for (a) an accurate description of the branching characteristics of the coronary network, (b) comparing the network with others in the cardiovascular system and (c) comparing the vasculature in the normal versus that in the diseased heart.

ISSN:1018-1172    

DOI:10.1159/000158673

出版商:S. Karger AG    

年代:1987

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158674

出版商:S. Karger AG    

年代:1987

数据来源: Karger