Release of prostaglandins I2 and E2 from the perfused mesenteric arterial bed of normotensive and hypertensive rats. Effects of sympathetic nerve stimulation and norepinephrine administration.

The spontaneous output of prostaglandin (PG) I2 from the perfused mesenteric arterial bed in vitro was significantly higher in hypertensive rats than in normotensive rats. Sympathetic nerve stimulation (at 1OHz) of the mesenteric arterial bed from normotensive rats caused a rapid and short-lived (less than 4 min) two-fold increase in PGI2 output and a smaller increase in PGE2 output. Sympathetic nerve stimulation (at 1OHz) of the mesenteric arterial bed from hypertensive rats failed to increase PGI2 and PGE2 output. It is not possible to conclude whether this lack of response is a cause or a result of hypertension. Surprisingly, norepinephrine administration stimulated PGI2 and PGE2 release from the mesenteric arterial bed of both normotensive and hypertensive rats. Obviously, differences exist in the responsiveness of rat mesenteric arteries to endogenous and exogenous norepinephrine concerning PG release between the normotensive and hypertensive states.