摘要:

Effects of nicotine and electrical transmural stimulation on isolated dog cerebral arteries were studied. Nicotine (5 × 10–8–10–4 m) usually evoked a phasic contraction in the basilar artery and a relaxation in the middle cerebral artery. The nicotine-induced contraction and relaxation were abolished by pretreatment with pentolinium (10–5 m) but not by tetrodotoxin (TTX) (10–7 m). Phentolamine (10–6 m) or bretylium (10–5 m) abolished or reversed the nicotine-induced contraction, and partially reduced the nicotine-induced relaxation. Electrical transmural stimulation elicited a phasic contraction in the basilar artery and a relaxation or slight contraction in the middle cerebral artery. The contraction induced by transmural stimulation was abolished by bretylium and TTX, and augmented by phentolmine. The relaxation was not inhibited by bretylium. The uptake of 3H-norepinephrine (3H-NE) by the basilar and middle cerebral arteries was markedly reduced by cocaine (3 × 10–6 m). Nicotine and transmural stimulation increased the tritium efflux from both arteries. The nicotine-induced increase in tritium efflux was inhibited by pentolinium. The increased efflux induced by transmural stimulation was abolished by TTX, attenuated by bretylium, and augmented by phentolamine. These results indicate that nicotine and transmural stimulation cause both vasoconstrictor and vasodilator effects in the dog cerebral arteries and that the vasoconstriction is mediated through an adr

ISSN:1018-1172    

DOI:10.1159/000158157

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The lysosomal contents of hog kidney cortex, which induce angionecrosis and/or an increase of vascular permeability, were obtained by differential centrifugation and osmotic shock treatment, and were purified by various chromatographic techniques and electrophoresis. The material producing an increase in vascular permeability of the rabbit skin was purified 600-fold over the homogenate; however, it showed practically no angionecrotic activity. Another substance producing angionecrosis without pressor activity was partially purified.

ISSN:1018-1172    

DOI:10.1159/000158158

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The cerebrovascular system (the extra- as well as intracerebral vessels) receives a well-developed innervation by the adrenergic (originating in the superior cervical sympathetic ganglia) and cholinergic nerves. In addition, recent immuno-histochemical studies have shown the presence of vasodilatory peptidergic nerve fibres. There may be an association of cerebral blood vessels also with various aminergic nerve systems of intracerebral origin. Besides the nerves, amine-containing mast cells are often located in close relation to the brain vessels. The specific receptors mediating the contractile and dilatory response of the various vasoactive amines – noradrenaline, dopamine, 5-hydroxytryptamine, histamine, acetylcholine – have been characterized in detail in pharmacological experiments. There is a number of major differences in the reactivity of cerebral vessels as compared to vasomotor functions in the peripheral circulation. The observations and results provide a basis for a better understanding of physiological neurogenic control mechanisms in the cerebral circulation, and they may also have implications for the interpretation of pathophysiological phenomena related to, for example, migraine and the vasospasm following subarachnoid hemorrh

ISSN:1018-1172    

DOI:10.1159/000158159

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Plasmatic arterionecrosis, the causative lesion of hypertensive cerebral hemorrhage, follows upon medial muscle cell necrosis. The development of medial muscle cell necrosis, the earliest cerebral arterial change seen in hypertensive rats, was inhibited when these animals were fed a cholesterol and lard-supplemented diet. Insudation of fibrin was noted in the arterial intima of hypertensive rats with bilaterally constricted renal arteries. Removal of the constriction induced a fall in the elevated blood pressure and an increase of intimal muscle cells. These were responsible for the dissolution of the deposited fibrin, leading to arteriosclerosis. These myointimal cells may originate from the endothelium. Arterial contraction caused by methoxamine hydrochloride often induced the intrusion of one medial muscle cell into another and increased endothelial permeability. 12–24 h after contraction, the arterial segments showed medial muscle cell necrosis, endothelial desquamation with platelet adhesion, and blood plasma infiltratio

ISSN:1018-1172    

DOI:10.1159/000158160

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The canine posterior vena cava was excised and divided into three embryologically distinct segments: segment A (supradiaphragm), segment B-C (intra-hepatic and that between liver and renal veins), and segment D (infrarenal). Circular and longitudinal strips were cut from each segment, suspended in Krebs bicarbonate solution and isometric tensions were recorded. The responses to six vasoactive agents, as well as transmural neural stimulation were studied. Maximum tension and ED50 were obtained for norepinephrine, epinephrine, acetylcholine, bradykinin, histamine and 5-hydroxytryptamine (5-HT). The responses were not only quantitatively, but qualitatively different among the three segments. Bradykinin constricted the strip:; in A and B-C but not in D. 5-HT (<10–5 m) caused a dose-dependent contraction in A and D through its direct stimulating action, while in C, a contractile response appeared only after administration of a higher dose of 5-HT. This was due to an indirect sympathomimetic action of the agent. Segment B-C, which histologically contained massive longitudinal muscle bundles in the outer layer of the wall, exhibited spontaneous, rhythmic contractions. The existence of a cholinergic excitatory innervation, in addition to adrenergic, was demonstrated in C by transmural neural stimulatio

ISSN:1018-1172    

DOI:10.1159/000158161

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Atherosclerosis was produced in rabbits by feeding 1% cholesterol pellets for 15 weeks to 35 male rabbits divided into two equal groups – the placebo control and phthalazinol group – with a comparable serum cholesterol level. The phthalazinol group was given 20 mg/kg of the compound daily. 13 rabbits of both groups were on 15 weeks of the treatment and the remaining 22 rabbits were treated for 30 weeks. The treated group exhibited a statistically significant increased removal of cholesterol from atherosclerotic aortas and improvement in pathological changes. This enhancing effect was more marked in the animals treated for 30 weeks. Such evidence indicates that there are substances capable of enhancing the removal of cholesterol from atheromatous lesions. In light of the pharmacological properties of phthalazinol, the possible role of thromboxane A2 released from platelets adhered and aggregated on atheromatous plaques, in the progression of atherosclerosis is worthy of continued investigat

ISSN:1018-1172    

DOI:10.1159/000158162

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Collagen synthesis was increased in aortas, mesenteric arteries, cerebral microvessels, pial artery, basilar artery and decreased in the heart of rats made hypertensive with deoxycorticosterone acetate-salt or the spontaneously hypertensive animal. The markers of collagen biosynthesis that were elevated were prolyl hydroxylase, prolyl hydroxylase-related antigen, total collagen content and the incorporation of labelled proline into total protein and into collagen. The antihypertensive drugs reserpine and chlorthiazide could both prevent the increase or reduce the increase in collagen synthesis.

ISSN:1018-1172    

DOI:10.1159/000158163

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Vasoconstrictor and vasodilator neuroeffector transmission occurs in a variety of modes. Models are presented depicting vascular segments under the direct control of a single or multiple innervation, or an indirect influence via secondary release of a vasoactive substance. The neuroeffector relationship in the rabbit portal vein is described to illustrate the coexistence of several modes of transmission. ATP or its congener is released from the nonadrenergic vasodilator nerves in this vein, possibly as the transmitter. Further, a similar substance is released from the adrenergic vasoconstrictor nerves. It possibly acts directly on smooth muscle cells to relax them, and on the nerve terminals to inhibit the adrenergic transmitter release. Evidence suggests that such purine-mediated feedback mechanism may also occur at many other adrenergic and nonadrenergic neuroeffector synapses.

ISSN:1018-1172    

DOI:10.1159/000158164

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

The correlation between phosphate metabolism and isometric contraction was investigated in helical strips from dog coronary artery. Adenosine triphosphate (ATP) and creatine phosphate (CP) contents of resting strips did not significantly change during anoxia. ATP content remained unchanged during potassium-contracture under aerobic conditions but was significantly reduced by anoxia. Pre-treatment with iodoacetate resulted in a striking reduction in ATP content with a less marked decrease in CP content. ATP-depleting effect of iodoacetate was reduced slightly by the addition of pyruvate, but contractile response was not restored. It is considered that high-energy phosphates provided by anaerobic glycolysis can meet the energy requirements of resting coronary vessels but are insufficient for maintaining active tension. In resting strips equilibrated for 2 h in oxygenated bath solution, the reactivity to KC1 and anoxia appears to be dependent on the availability of ATP.

ISSN:1018-1172    

DOI:10.1159/000158165

出版商:S. Karger AG    

年代:1978

数据来源: Karger

摘要:

Helical strips of rat tail artery were observed to relax in response to potassium after contraction induced by 10–7 g/ml norepinephrine in potassium-free solution. After several minutes of relaxation, the strips showed an abrupt redevelopment of tension. The amplitude of the potassium-induced relaxation was employed as an index of the activity of the electrogenic sodium-potassium pump and hence of the Na+-K+ ATPase. This assumption seemed justified because the observed amplitude of potassium-induced relaxation paralleled known effects of the following variables on Na+-K+ ATPase: (1) intracellular sodium concentration; (2) ouabain administration; (3) magnesium; (4) temperature, and (5) potassium concentration. The relaxation that occurred in response to potassium is suggested to be due to an enhanced Na+-K+ ATPase resulting in increased electrogenic transport of sodium and potassium and, consequently, hyperpolarization. We propose that potassium-induced relaxation of rat tail artery may be used as a functional indicator of Na+-K+ ATPase activity in vascular smooth muscl

ISSN:1018-1172    

DOI:10.1159/000158166

出版商:S. Karger AG    

年代:1978

数据来源: Karger