Quarterly journal of experimental physiology and cognate medical sciences
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Q J Exp Physiol Cogn Med Sci · Jul 1980
Effects of starvation on cardiovascular function (including the mammary circulation) and water balance in pregnant goats.
In conscious goats, starved for 48 hr, in mid-pregnancy (70 days) cardiac output and blood volume decreased; total peripheral resistance increased; heart rate, stroke volume, blood pressure, mammary blood flow and mammary resistance were not significantly affected. In late pregnancy (132 days) cardiac output, heart rate, blood volume and mammary blood flow fell; peripheral resistance increased; stroke volume and blood pressure were not significantly affected. In mid-pregnancy, water consumption fell and the animal entered a stage of negative sensible water balance which persisted for both days of starvation. ⋯ Cardiac output, heart rate, blood volume and mammary blood flow was higher in fed late-pregnant than in fed mid-pregnant goats, total peripheral resistance was lower while there were no significant changes in stroke volume or blood pressure. Indications of correlations between litter size and cardiac function were obtained. The results are compared with previous studies on the effects of starvation in lactating animals and are discussed in relation to the control of cardiac function and mammary blood flow in pregnancy and lactation.
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Q J Exp Physiol Cogn Med Sci · Oct 1976
Changes in arterial blood pressure, heart rate and haematocrit during acute hyperkalaemia in conscious sheep.
The systolic, diastolic and mean arterial blood pressures, heart rate and haematocrit were measured at 15 minute intervals before, during and after 2 hour infusions of 0-4 mol.l-1 NaCl at 2-2 ml min-1 into conscious intact sheep and 0-4 mol. l-1 KCl at 2-2 ml. min-1 into conscious sheep which were either intact or adrenalectomized. The haemotocrit was also measured in splenectomized sheep receiving 0-4 mol. l-1 KCl. The NaCl infusion had no significant effect on blood pressure(BP), heart rate and haematocrit. ⋯ Heart rate and haematocrit were more closely correlated with the plasma potassium concentration than with any other variable measured in these experiments. Adrenalectomy did not reduce the ability of the sheep to maintain their BP or to increase their heart rate and haematocrit. As the mean increase in haematocrit during potassium infusion into splenectomized sheep was 1-3+/-0-45% most of the increase in haematocrit observed in the potassium-infused intact and adrenalectomized sheep was caused by ejection of red cells from the spleen into the circulation.
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Q J Exp Physiol Cogn Med Sci · Jan 1976
Changes in urinary water and electrolyte excretion in sodium-loaded sheep in response to intravenous infusion of arginine vasopressin.
Mature sheep receiving supplements of sodium chloride into the rumen were given intravenous infusions of arginine vasopressin at rates varying from 4-6-23 pmol/min (2-10 mU/min). Infusion of the hormone led to an increase in urine flow and to increases in the amounts of sodium and chloride excreted, the effect on flow was, however, the greater so that the osmolality of the urine fell during the infusions. In sheep given intravenous infusions of a hypertonic sodium chloride solution addition of vasopressin to the infusate led to the formation of a larger volume of urine containing a higher proportion of the infused salt load compared to when the salt solution alone was given. ⋯ Plasma vasopressin levels markedly increased during these infusions, the levels seen being similar to those seen in sheep given vasopressin in amounts which increased both urine flow and electrolyte excretion. This suggests that during hypertonic salt loading vasopressin probably contributes directly to the increases in urine flow and the increases in electrolyte excretion which are seen. Further evidence in support of this was obtained in experiments in which a greater natriuretic response was seen in sheep given a hypertonic sodium chloride solution into the carotid artery as opposed to the given a hypertonic sodium chloride solution into the carotid artery as opposed to the jugular vein and where it was shown that plasma vasopressin levels were indeed higher when the solution was given into the artery.