Vasodilation of the rat mesenteric vasculature by parathyroid hormone.

摘要: The isolated, perfused rat mesenteric vascular bed was used as a sensitive model of resistance vessel dynamics to evaluate the actions parathyroid hormone (PTH). Periarterial sympathetic nerve stimulation (PNS) carried out at 8 Hz, 2 msec in pulse duration (supramaximal voltage) for 30 sec. pressor response PNS decreased dose-dependent fashion by synthetic bovine PTH(1-34). Reduction greater than 30% nM PTH. concentration PTH required produce half-maximal (ED50) decrease PNS-induced tone 4 nM. phosphodiesterase inhibitor, methylisobutylxanthine, 300 did not alter when given alone, but potentiated action. Isoproterenol (1 microM) only 20%. Propranolol inhibited effect isoproterenol on response, that inhibitory analog PTH, bPTH(7-34), blocked action completely 30- 50-fold higher concentrations also norepinephrine infusion, similar effects PNS. Again, bPTH(7-34) vasoconstriction. These findings indicate has efficacy and potency reducing activity vasculature demonstrate significant nanomolar concentrations.