Effects of leukotriene C4 and prostaglandin E2 on the rat mesentery in vitro and in vivo.

Leukotriene C4 (LTC4) and Prostaglandin E2 (PGE2) have been studied for their effects on the rat mesentery in vitro and in vivo. Their effects on the norepinephrine (NE) induced vasoconstrictions in the above vascular bed have also been investigated. LTC4 (10(-10)M) and PGE2 (2.8 X 10(-7)M) produced no direct effects on the perfusion pressure in the isolated perfused rat mesentery. However, LTC4 (10(-10)M) produced constriction of the arterioles in vivo. PGE2 (2.8 X 10(-7)M) did not produce any direct effect on the microcirculation. Indomethacin, when superfused for 10 min. in a concentration of 7 X 10(-5)M, produced significant arteriolar constriction; this effect was reversed when PGE2 was added to the superfusing media containing indomethacin. LTC4, perfused in a concentration of 10(-10)M, produced a time - dependent inhibitory effect on NE induced vasoconstrictions in vitro whereas PGE2 perfusions (2.8 X 10(-7)M) potentiated the NE responses. This potentiating effect of PGE2 was inhibited by indomethacin. In contrast, the topical application of PGE2 in vivo attenuated NE responses of the mesenteric arterioles.