Effects of parathyroid hormone-related protein on systemic and regional hemodynamics in conscious rats. A comparison with human parathyroid hormone.

PTHrp was discovered as a humoral hypercalcemic factor of malignancy and has been shown to bind the same receptor as PTH in rat bone cells, canine renal membranes, and rabbit renal microvessels. We investigated the global effect of human PTH(hPTH) and PTHrp on systemic and regional hemodynamics in conscious rats. The hypotensive response to PTHrp was more potent than that to hPTH. Although hPTH (15 micrograms/kg/min, i.v.) caused a significant increase in cardiac output, whereas PTHrp (5 micrograms/kg/min, i.v.) caused no change in cardiac output despite a similar hypotensive effect to hPTH, the effects of PTHrp and hPTHrp on regional hemodynamics were quite similar, and both peptides had a prominent vasodilatory effect on the coronary and hepatic arteries. Therefore, PTHrp appears to have an important role in blood pressure and regional hemodynamics as does hPTH.