The acute effects of intravenous infusion of parathyroid hormone on urine, plasma and saliva in the sheep.

Following an intravenous loading injection of 75 U.S.P. Units of Para-Thor-Mone (Eli Lilly and Co), seven conscious, non-pregnant, non-lactating Merino ewes were infused with a maintenance dose of the hormone at a rate of 4-75 U.S.P. units/min for 2 hr. The classical hypercalcaemia and hypophosphataemia of the non-ruminant was observed, but the hypercalcaemi- was only small. Plasma potassium concentration decreases, while there were no changes in plasma sodium, chloride or mangesium. The classical phosphaturic effect of the hormone was not observed, only trace amounts of phosphate being exreted throughout the experiment. Urinary excretion of calcium and magnesium decreased, urine flow and urinary excretion of sodium, potassium, chloride, bicarbonate and urine pH increased. Glomerular filtration rate was unaffected, but renal plasma flow increased. The concentration and secretion rate of salivary phosphate increased markedly. Changes in the other important salivary electrolytes (sodium, potassium, chloride, bicarbonate and hydrogen ion) also occurred, but it was difficult to separate primary from secondary effects of the hormone. Saliva flow rate increased transiently following hormone injection, but the effect was not sustained by the maintenance infusion.