AJP - Renal Physiology, Vol 248, Issue 5 674-F681, Copyright © 1985 by American Physiological Society
Effect of PTH on blood pressure and response to vasoconstrictor agonists
Y. Saglikes, S. G. Massry, K. Iseki, J. L. Nadler and V. M. Campese
Parathyroid hormone (PTH) is known to be a vasodilator and to exert a
hypotensive action. The present study examined the possible mechanisms
involved, with special emphasis on the role of vasodilatory prostaglandins.
The effects of the intact 1-84 PTH and that of its amino-terminal 1-34
fragment on mean arterial pressure (MAP) and on the vascular response to
norepinephrine (NE) or angiotensin II (ANG II) were examined in rats before
and after pretreatment with indomethacin. Bolus injections of 30 U of both
1-84 and 1-34 PTH produced a significant (P less than 0.01) decrease in
MAP; however, the hypotensive response to 1-34 PTH (-28 +/- 4.6 mmHg) was
more marked (P less than 0.01) than to 1-84 PTH (-9 +/- 1.8 mmHg). The
infusion of 1-84 PTH (30 U/h) did not alter MAP, whereas the infusion of
1-34 PTH (30 U/h) led to a decrease in MAP from 124 +/- 2 to 103 +/- 4.0
mmHg (P less than 0.01) and to a rise in heart rate from 359 +/- 30 to 437
+/- 13 beats/min (P less than 0.02). Both 1-84 and 1-34 PTH antagonized the
pressor effects produced by bolus injections of NE and ANG II. Pretreatment
with indomethacin (5 mg/kg body wt) abolished the inhibitory effect of 1-84
and 1-34 PTH on the response of MAP to NE and ANG II and the hypotensive
action of 1-34 PTH. Infusion of 1-84 and 1-34 PTH produced a significant
rise in urinary excretion of 6-keto-PGF1 alpha.(ABSTRACT TRUNCATED AT 250
WORDS)
