PARATHYROID HORMONE-RELATED PEPTIDE INCREASES URINARY PHOSPHATE EXCRETION IN FETAL LAMBS

The effect of synthetic human parathyroid hormone-related peptide frag ment 1-34 (hPTHrP) on plasma concentration and urinary excretion of in organic phosphorus (P) was compared to that of synthetic bovine PTH fr agment 1-34 (bPTH) in four 120- to 130-day-old fetal lambs chronically catheterized in utero. They received by i.v. infusion according to a Latin square design either bPTH (6 nmol per fetus) or hPTHrp (6 nmol p er fetus) alone, or after the synthetic analogue [Tyr34]bPTH(7-34)NH2 (12 nmol per fetus). Control fetuses received the same volume of solve nt alone. Both bPTH and hPTHrP stimulated diuresis. They induced hyper calcaemia, hyperphosphaturia and hypophosphataemia. The effects of hPT HrP were inhibited by [Tyr34]bPTH(7-34)NH2, indicating that PTHrP migh t work through the PTH receptor.