Enhancement of Neural and Thermal Vasoconstriction by Prostaglandin B 1 1 2

Abstract

Summary

The vascular effects of prosta-glandin B₁ (PGB₁) were studied during constant-flow perfusion of the canine hind-paw. The effects of PGB₁ (50-200 ng/kg/ min ia) on systemic and hindpaw perfusion pressures and on responses to local cooling (4°C for 90 sec) and local heating (45°C for 60 sec) were measured in 15 dogs. PGB₁ (50-100 ng/kg/min) decreased perfusion pressure without any significant effect on systemic arterial pressure. Higher concentrations of PGB₁ (200 ng/kg/min) elevated perfusion pressure to control values. The pressor responses to local cooling were increased from 11 to 32 mmHg while the dilator responses to local heating and nitro-glycerin were reduced during infusions of PGB₁. PGB₁ also enhanced the pressor responses to norepinephrine or tyramine. These findings support the conclusions that (1) low concentrations of prostaglandin B₁ enhance neurotransmitter release with minimal effects on vascular smooth muscle cells and (2) these effects are not secondary to increased perfusion pressures or vascular wall stresses since infusions of PGB₁ resulted in vasodilation.

The generous supply of prostaglandin B used in this study was donated by Drs. J. R. Weeks and J. E. Pike of the Upjohn Company.