摘要:

Microsomal fractions enriched in plasma membranes and endoplasmic reticulum were isolated from stomach fundus and vas deferens from age-matched Okamoto spontaneously hypertensive (SHR) rats and corresponding Kyoto-Wistar normotensive rats (KWR). Alterations of several enzyme activities and Ca2+ accumulation of the isolated microsomal fraction from these nonvascular smooth muscles provide direct evidence of abnormal smooth muscle membrane biochemistry in SHR. Decreased Ca2+ accumulation in the presence of but not in the absence of adenosine triphosphate by the microsomal fractions of both fundus and vas deferens from SHR is consistent with previous findings using plasma membranes from vascular smooth muscles from SHR and cannot be explained in terms of adaptation induced by elevation of blood pressure in SHR. Defective Ca2+ handling now observed in both vascular and nonvascular smooth muscles from hypertensive animals not only provides a cellular basis for the altered reactivity and contractility of smooth muscles observed in SHR, but also supports the hypothesis that spontaneous hypertension is associated with a generalized widespread alteration in smooth muscle membrane fraction.

ISSN:1018-1172    

DOI:10.1159/000158394

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

In experiments with adult rabbits the active microvascular segments located at particular sites of the minor pial arterial ramifications were investigated. These appeared as sphincters at off-shoots of the arterial branches, the precortical arteries, and the arterial microanastomoses. The sphincters and the precortical arteries were found plentifully supplied with the cholinergic and adrenergic nerves, but the innervation of the microanastomoses was not considerably different from that of the adjacent arterial branches. The nerves of the precortical arteries were in direct connection with the nerve fibers of the arterial branches located inside the cerebral cortex. The pattern of distribution and innervation of the active vascular portions in pial microvascular bed suggests the probability of a neurogenic control of the blood supply to the smallest areas of the cerebral cortex.

ISSN:1018-1172    

DOI:10.1159/000158395

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

In 13 isolated, perfused guinea pig hearts we determined the coronary flow responses to abrupt elevation of perfusate potassium levels (final concentration 12–16 mM) in the absence and presence of adenosine, and during hypoxic perfusion. Control diastolic coronary flow and spontaneous heart rate averaged 7.85 ± 0.26 ml/min/g and 249.6 ± 2.4 beats/min, respectively. Potassium infusion (12–16 mM) in the absence of other intervention did not alter coronary flow significantly. Repeat potassium elevation in the presence of 0.05 and 0.1 µM adenosine (threshold dilating doses) produced respective flow increases of 58 and 43% above normokalemic flow (p < 0.05). Paradoxically, during hypoxic perfusion (70%, O2 or 45 % O2 in the gas phase) potassium did not elevate flow and, in some instances, constricted the vessels. Myocardial oxygen consumption and effluent potassium levels did not change with adenosine or hypoxic perfusion. These results suggest two points: (1) an interaction between potassium ion and adenosine may be important in the regulation of coronary flow and (2) hypoxic dilation in the coronary vasculature may act via a mechanism different from that of ade

ISSN:1018-1172    

DOI:10.1159/000158396

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Spontaneous electrical activity was recorded intracellularly in vitro from smooth muscle cells of guinea pig small pressurized mesenteric arteries. Spontaneous action potentials were recorded at 37 °C at frequencies of 30–55/min. Each action potential consisted of a prepotential (pacemaker potential) followed by a spike of variable amplitude (10–35 mV). This activity was not blocked by tetrodotoxin (TTX) or guanethidine, indicating it was myogenic in origin. Sympathetic nerve stimulation (single 0.5-ms field stimuli) could evoke action potentials in between the spontaneous action potentials and could drive the activity; this effect was blocked by TTX. Addition of the vasodilator adenosine (10–6 to 10–4M) reversibly decreased action potential amplitude and frequency. Lowering the temperature to 35 °C for 1–3 min during a single impalement decreased spontaneous action potential frequency. Spontaneous activity was abolished after longer periods at 35 °C. The spontaneous activity recorded in vitro at 37 °C and 5 or 40 mm Hg inflation pressure was similar to that previously reported from guinea pig and rat mesenteric arteries in vivo. Such activity might be important in the normal physiological control of

ISSN:1018-1172    

DOI:10.1159/000158397

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Tibial arteries removed from normotensive dogs and from two-kidney one clip Goldblatt hypertensive dogs, 6–34 days after renal artery constriction, were studied in vitro. Contractions were elicited by transmural stimulation and norepinephrine added to the organ bath. Arteries from the hypertensive dogs exhibited depressed responsiveness to adrenergic nerve stimulation, but not to the lower concentrations of norepinephrine. However, the maximal response to norepinephrine was decreased as has been previously observed in hypertensives’ arteries. The results indicate that pre- and postsynaptic factors are involved in the depressed adrenergic responses in the hypertensives’ tibial art

ISSN:1018-1172    

DOI:10.1159/000158398

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158399

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158400

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158401

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158393

出版商:S. Karger AG    

年代:1982

数据来源: Karger