Direct vasoconstrictor effect of prostaglandin E2 on renal interlobular arteries: role of the EP3 receptor

Evidence indicates that prostaglandin E2 (PGE2) preferentially affects preglomerular renal vessels. However, whether this is limited to small-caliber arterioles or whether larger vessels farther upstream also respond to PGE2 is currently unclear. In the present study, we first investigated the effects of PGE2 along the preglomerular vascular tree and subsequently focused on proximal interlobular arteries (ILAs). Proximal ILAs in hydronephrotic rat kidneys as well as isolated vessels from normal kidneys constricted in response to PGE2, both under basal conditions and after the induction of vascular tone. By contrast, smaller vessels, i.e., distal ILAs and afferent arterioles, exhibited PGE2-induced vasodilation. Endothelium removal and pretreatment of single, isolated proximal ILAs with an EP1 receptor blocker (SC51322, 1 μmol/l) or a thromboxane A2 receptor blocker (SQ29548, 1 μmol/l) did not prevent vasoconstriction to PGE2. Furthermore, in the presence of SC51322, responses of these vessels to PGE2 and ...