Distinct hemodynamic and renal effects of calcitonin gene-related peptide and calcitonin in men

Cardiovascular and renal actions of human calcitonin gene-related peptide II (or beta) (CGRP) and of human calcitonin (CT) infused intravenously for 1 h each (79 and 263 pmol.kg-1.h-1) have been compared in normal men (n = 10 for CGRP, n = 6 for CT and vehicle alone). CGRP lowered diastolic blood pressure by 26% and increased the heart rate by 35% and raised plasma levels of norepinephrine, epinephrine, and dopamine and renin activity (P less than 0.01). The fractional excretion rates (FE) of sodium and chloride were doubled (P less than 0.05-0.01) in the presence of an unaltered glomerular filtration rate. CT, on the other hand, did not affect the diastolic blood pressure, but the stimulation of diuresis and of the FE of sodium and chloride was more pronounced with CT than with CGRP (P less than 0.01). Moreover, CT lowered serum calcium levels and stimulated urinary adenosine 3',5'-cyclic monophosphate and phosphate excretion (P less than 0.01). In conclusion, the cardiovascular effects of CGRP are contrasted by weaker renal tubular actions of the neuropeptide in relation to CT.