Search PubMed⌕ Search

Biomedical subjects

J Bligh

Publications and source records attributed to J Bligh.

At least 91 records · Page 5Linked to original sources
PubMed1979

Effect of intraventricular injection of transmitter substances and temperature on autonomic functions of conscious sheep.

1. Changes in cardiovascular and renal functions following injection of noradrenaline, 5-hydroxytryptamine and carbachol into one lateral cerebral ventricle were investigated in conscious sheep at ambient air temperatures of 0 and 40 degrees C. The dose rates used were known to produce predictable changes in thermoregulation in sheep. 2. The changes in body temperature, respiratory frequency and shivering caused by the intracerebroventricular (I.C.V.) injections of noradrenaline, 5-hydroxytryptamine and carbachol were as reported previously. 3. The cardiovascular and renal responses of the sheep at both high and low ambient temperatures were consistent for each transmitter indicating that these activities had no major dependence on the type of thermoregulatory response. 4. I.C.V. injection of noradrenaline increased heart rate and decreased pulse pressure but caused no change in mean arterial blood pressure (B.P.). Urine flow rate, sodium clearance, potassium clearance and osmolal clearance were decreased whereas solute-free water reabsorption was unaltered. 5. I.C.V. injection of 5-hydroxytryptamine caused no significant alterations in either cardiovascular or renal function. 6. I.C.V. injection of carbachol increased systolic and diastolic B.P., heart rate and haematocrit. Sodium, potassium and osmolal clearances were increased after administration of carbachol. 7. The changes in renal function after noradrenaline and carbachol injection could be explained by the concurrent changes in cardiovascular function.

Animals↗
PubMed1979

Aspects of thermoregulatory physiology pertinent to hyperthermic treatment of cancer.

Local hyperthermia is relatively safe, while whole-body hyperthermia is potentially dangerous because the therapeutically effective elevation of body temperature is close to the tolerable limit to hyperthermia beyond which permanent damage may be caused. Here consideration is given to the most reliable index of body temperature during hyperthermia and the techniques for raising body temperature. The possibility of effecting local brain cooling and thereby increasing the margin of safety during whole-body hyperthermia is also considered.

Animals↗
PubMed1978

Comparison of the thermoregulatory responses to intracerebroventricularly injected dopamine and noradrenaline in the sheep.

The thermoregulatory effects of dopamine (DA), given by intracerebroventricular (i.c.v.) injection to sheep, have been examined and compared with those of i.c.v. noradrenaline (NA). At ambient temperatures (Ta) of 20 degrees and 30 degrees C both DA (200 nmol . kg-1) and NA (100 nmol . kg-1) induced constriction of the ear vessels, a decrease in respiratory frequency and an increase in rectal temperature (Tr). At Ta of 10 degrees and 0 degrees C both substances caused a decrease in heat production and a fall in Tr. The DA receptor blocker spiroperone (30 nmol . kg-1, i.c.v.), which itself had a vasodilatatory effect at 20 degrees C Ta, blocked the peripheral vasoconstriction and slightly attenuated the rise in Tr normally caused by i.c.v. DA or NA at this Ta, but did not eliminate the suppression of respiratory frequency. During i.c.v. infusion, at 20 degrees C Ta, with the DA-beta-hydroxylase inhibitor FLA-63, the effect of i.c.v. DA on Tr was attenuated, while that of NA was enhanced. These results suggest that in sheep central thermoregulatory system there are DA receptors which stimulate the pathway that controls peripheral vasomotor tone. The inhibitory effect of NA and DA on heat production and evaporative heat loss is probably mediated by noradrenergic receptors, which can also be activated by DA both directly and after its conversion to NA.

Animals↗
PubMed1978

Adipose tissue cells in cold-acclimatised sheep.

The morphology and lipid content of adipose tissue from sheep subjected to cold acclimatisation were examined. In two sheep the perirenal adipose tissue contained virtually no triglyceride (less than 2 mg/100 mg wet tissue) and the appearance on electron microscopy was typical of that of a depleted white fat cell. The morphological, chemical and physiological evidence indicates that, in the sheep, white adipose tissue does not revert to brown adipose tissue during depletion resulting from cold acclimatisation.

Acclimatization↗
PubMed1977

Electrolyte concentrations in sheep cerebrospinal fluid.

Cerebrospinal fluid (csf) of sheep was obtained by acute lumbar puncture and from chronic cannulations of the lateral cerebral ventricle. The concentrations of ions in the csf including chloride which had previously been reported to be very high, were found to be similar to those of other mammals and were not greatly affected by changes in plasma electrolyte composition associated with adrenalectomy.

Adrenalectomy↗
PubMed1976

Interaction between the effects of spinal heating and cooling and of injections into a lateral cerebral ventricle of noradrenaline, 5-hydroxytryptamine and carbachol on thermoregulation in sheep.

1. A study has been made of the interactions of the thermoregulatory effects of spinal cord heating and cooling and of the injections into the cerebral ventricle of noradrenaline, 5-hydroxytryptamine (5-HT) and carbamylcholine in sheep. 2. The interactions of spinal cord heating and the injections into the cerebral ventricle of noradrenaline, 5-HT and carbamylcholine were very similar to those of hypothalamic heating or of high ambient temperature and the injections into the cerebral ventricle of these substances. These results are interpreted as evidence of the synaptic convergence of the pathways from peripheral, spinal cord and hypothalamic warm-sensors at or before the points of action of these synaptically active substances. 3. The only definite thermoregulatory effect of spinal cooling was the onset of shivering which could be due to a purely spinal effect of cold. No substantial evidence was obtained of an interaction between spinal cooling and an injection of noradrenaline, 5-HT or carbamylcholine into the cerebral ventricle. Thus there was no clear indication of centripetal pathways from spinal cold sensors converging with those from the skin and the hypothalamus for which evidence of convergence was obtained in an earlier study. 4. The results of this study are expressed in terms of the neuronal model of Bligh, Cottle & Maskrey (1971) and Maskrey & Bligh (1971), appropriately modified.

Animals↗
PubMed1976

An additive effect of cold exposure and hypoxia on pulmonary artery pressure in sheep.

When shorn sheep were exposed to cold (3 degrees C) pulmonary artery pressure (PPA) increased by 24 per cent. When they were caused to breathe an air mixture containing only 11 per cent oxygen there was a similar rise in PPA (27 per cent). During simultaneous exposure to 3 degrees C and low oxygen tension, the rise in PPA was greater than the sum of the two separate treatments (61 per cent). These results indicate the possible significance of cold exposure in the occurrence of high mountain sickness.

Animals↗