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Biomedical subjects

C Rosendorff

Publications and source records attributed to C Rosendorff.

At least 73 records · Page 4Linked to original sources
PubMed1978

Vasodilator mechanism of the intracerebral (non-sympathetic) adrenergic pathway.

Stimulation of the intracerebral noradrenergic pathway causes a vasodilatation in the hypothalamus. We have investigated whether this vasodilatation is caused by a direct vascular innervation or whether it is secondary to an activation of hypothalamic neurons. Non-specific neuronal activation using glutamate increased the mean hypothalamic blood flow. Depression of neuronal activity using barbiturate reduced hypothalamic blood flow and blocked the glutamate and the intracerebral noradrenergic pathway-induced vasodilatation. These results suggest that stimulation of the intracerebral noradrenergic pathway increases hypothalamic neuronal activity which indirectly causes a vasodilatation.

Animals↗
PubMed1977

A dissociation between temperature regulation and fever in the rabbit.

1. The role of 5-hydroxytryptamine (5-HT) in temperature regulation and in fever in the rabbit has been investigated. 2. Intrahypothalamic microinjections of 5-HT in the conscious rabbit alters body temperature in a dose-dependent manner. 3. Low doses (5-5nmol) of 5-Ht and control saline injections produced a small, non-significant increase in temperature, with a long latency. 4. Doses of 14 nmol 5-HT produce a hyperthermia with a 45 min delay; while microinjections of 28 nmol result in a biphasic response; an initial short hypothermia is followed later by a hyperthermia. 5. Depleting the rabbit's brain of 5-HT by pretreatment with p-chlorophenylalanine (PCPA) fails to affect its body temperature at thermoneutral temperatures but significantly impairs the ability to thermoregulate against a cold stress. 6. PCPA pretreatment did not, however, impair the febrile response to bacterial pyrogen and prostaglandin E1. 7. These results reveal a dissociation between the effects of 5-HT depletion on temperature regulation, and on fever. The site of action of 5-HT in temperature regulation must be proximal to the fever input, but distal to the convengence of peripheral and hypothalamic temperature inputs.

Animals↗
PubMed1977

Effects of prostaglandin antagonism on sodium arachidonate fever in rabbits.

1. Sodium arachidonate, the prostaglandin precursor substance, when injected intraventricularly into rabbits, results in dose-dependent hyperthermia, which is rapid in onset and of several hours duration. 2. Arachidonate fever was inhibited by intraventricular injection of indomethacin, but not by the simultaneous intraventricular injection of either of the two prostaglandin antagonists SC 19220 or HR 546. 3. Both antagonists effectively inhibited the fever induced by the intraventricular injection of an equipotent dose of PGE1. 4. Our results show that a derivative of arachidonic acid other than prostaglandin is pyrogenic.

Animals↗
PubMed1976

The effect of an inhibitor of adenylate cyclase on the development of pyrogen, prostaglandin and cyclic AMP fevers in the rabbit.

An exotoxin of Bacillus thuringiensis known to inhibit adenylate cyclase in vitro has been used to investigate the role of cyclic AMP in the pathogenesis of fever in the rabbit. Intra-hypothalamic microinjections of the exotoxin are non-pyrogenic and significantly attenuate the hyperthermia caused by intrahypothalamic microinjections of both bacterial pyrogen (endotoxin) and prostaglandin E1. The hyperthermia produced by dibutyrl cyclic AMP is not affected by the exotoxin. These results support the idea that adenylate cyclase is activated during the development of fever in the rabbit.

Adenine Nucleotides↗
PubMed1976

Comparison of indoramin and methyldopa in hypertension.

A comparison of indoramin and methyldopa in the treatment of mild and moderate essential hypertension in 31 White middle-aged patients was made by means of a double-blind crossover trial. Equally satisfactory control of systolic and diastolic blood pressure, in the standing and supine positions, was achieved by both drugs. With a mean dose of 158 +/- 9 mg per day of indoramin the average fall in lying and standing blood pressures was 16/6 and 16/8 mmHg respectively. Equivalent values for methyldopa, with a mean dose of 1 540 +/- 90 mg per day, were 21/8 and 16/13 mmHg. Values for the two drugs are not significantly different. Also, there were no significant differences between the two drugs in their effect on the heart rate or in the incidence of side-effects.

Aged↗
PubMed1976

Effects of hypertensive plasma on the responses of an isolated artery preparation to noradrenaline.

The effect of hypertensive plasma on the responses of an isolated artery preparation to noradrenaline were studied. In addition, because of the association between hypercholesterolaemia and hypertension, the effect of pure cholesterol and low density lipoprotein on the arterial responses to noradrenaline was also investigated. Both hypertensive plasma and low density lipoprotein potentiated the responses of the arterial preparation to noradrenaline.

Animals↗
PubMed1976

Evidence for a dual innervation affecting local blood flow in the hypothalamus of the conscious rabbit.

We have attempted to evaluate the role of adrenergic nerves which arise from the superior cervical ganglia or which are intracerebral throughout their course, in the control of local cerebral blood flow (CBF). Hypothalamic blood flow (HBF) was measured in the conscious rabbit by the 133Xe-clearance technique. Stimulation of the upper brainstem, using 5-Hz, 3-V, 1-msec, square wave pulses, increased by HBF by a mean of 7.6 ml/100 g per min (P less than 0.005). This effect was abolished by the intrahypothalamic injection of the beta-adrenoreceptor blocker, propranolol, and by chemical sympathectomy of the hypothalamus or of the upper brainstem with 6-hydroxydopamine, but was not altered by bilateral cervical ganglionectomy. Intrahypothalamic injection of 0.1 mug of tyramine caused a mean decrease in HBF of 15.6 ml/100 g per min (P less than 0.001). This effect of intrahypothalamic injection of tyramine was abolished by bilateral cervical sympathectomy but not by chemical sympathectomy of the upper brainstem. These results support the idea that local CBF, at least in the hypothalamus, is mediated by two distinct pathways. The first consists of the sympathetic nerves which arise in the cervical ganglia, and which activate intrahypothalamic alpha-receptors to cause constriction. The second is an entirely intracerebral noradrenergic pathway which stimulates beta-receptors to cause vasodilation.

Animals↗
PubMed1976

Noradrenaline sensitivity of an isolated perfused artery: effects of normal and hypertensive plasma.

1. The noradrenaline sensitivity of the isolated perfused rabbit artery was studied, during perfusion with Krebs solution, normal plasma, hypertensive plasma and a low-density lipoprotein (LDL) extract of normal plasma. 2. There was no difference in noradrenaline sensitivity between arteries perfused with Krebs and normal plasma. 3. Both hypertensive plasma and LDL potentiated the noradrenaline-induced vasoconstriction. 4. This potentiation was associated with increases in both the intrinsic activity of the drug-receptor complex and the drug-receptor affinity. 5. There is a circulating factor in the plasma of hypertensive patients which sensitizes arteries to noradrenaline, and this factor may be LDL.

Animals↗
PubMed1975

The effects of jaundiced plasma and hypercholesterolaemic plasma on vascular sensitivity to injected noradrenaline.

Jaundiced plasma and plasma from hyperlipidaemic patients was perfused into an isolated artery or kidney preparation. The responses of the artery to doses of noradrenaline when Krebs solution was perfused were compared to the responses when the plasmas were perfused. It was found that both jaundiced and hyperlipidaemic plasmas potentiated the effects of noradrenaline on the isolated arteries and kidneys.

Animals↗