Prostaglandin E₂sequentially activates E‐prostanoid receptor‐3 and thromboxane prostanoid receptor to evoke contraction and increase in resistance of the mouse renal vasculature

Abstract

Although recognized to have an in vivo vasodepressor effect blunted by the vasoconstrictor effect of E-prostanoid receptor-3 (EP3), prostaglandin E 2 (PGE 2 ) evokes contractions of many vascular beds that are sensitive to antagonizing the thromboxane prostanoid receptor (TP). This study aimed to determine the direct effect of PGE 2 on renal arteries and/or the whole renal vasculature and how each of these two receptors is involved in the responses. Experiments were performed on isolated vessels and perfused kidneys of wild-type mice and/or mice with deficiency in TP (TP −/− ), EP3 (EP3 −/− ), or both TP and EP3 (TP −/− /EP3 −/− ). Here we show that PGE 2 (0.001-30 μM) evoked not only contraction of main renal arteries, but also a decrease of flow in perfused kidneys. EP3 -/diminished the response to 0.001-0.3 μM PGE 2 , while TP −/− reduced that to the prostanoid of higher concentrations. In TP −/− /EP3 −/− vessels and perfused kidneys, PGE 2 did not evoke contraction but instead resulted in vasodilator responses. These results demonstrate that PGE 2 functions as an overall direct vasoconstrictor of the mouse renal vasculature with an effect reflecting the vasoconstrictor activities outweighing that of dilation. Also, our results suggest that EP3 dominates the vasoconstrictor effect of PGE 2 of low concentrations (≤0.001-0.3 μM), but its effect is further added by that of TP, which has a higher efficacy, although activated by higher concentrations (from 0.01 μM) of the same prostanoid PGE 2 . K E Y W O R D S EP3, gene deficiency, PGE 2 , renal vasoconstriction, TP | 2569 LIU et aL. How to cite this article: Liu B, Wu X, Zeng R, et al. Prostaglandin E 2 sequentially activates E-prostanoid receptor-3 and thromboxane prostanoid receptor to evoke contraction and increase in resistance of the mouse renal vasculature.

Differential properties of E prostanoid receptor‐3 and thromboxane prostanoid receptor in activation by prostacyclin to evoke vasoconstrictor response in the mouse renal vasculature

“…In WT vessels, the EP3 antagonist L798106 but not the EP1 antagonist SC19220 (either of them has a non-selective effect on TP) added to the effect of TP antagonism, 15,17,34 which rules out an involvement of EP1 and suggests that the activation of EP3 is a natural property of PGI 2 as we revealed with other PGs previously. 15,29,30 Moreover, the results of PGI 2 or its analogue and IP agonist iloprost obtained with perfused kidneys together with findings in renal arteries suggest that PGI 2 can cause an overall direct vasoconstrictor effect on the mouse renal vasculature and the dilator activity outweighed by activities of TP and EP3 results from IP as in some other vascular beds. 15,17,19 Also worthy of mention is that while PGI 2 evoked contraction from ~0.001-0.01 µM in PE-precontracted WT renal arteries, it caused relaxation at 0.01-1 µM in EP3 −/− counterparts.…”

“…The responses of mouse mesenteric arteries where EP3 has limited expression were also determined. 29,30 As shown in Figure 4B, in NOS-inhibited, PE (1 µM) precontracted WT mouse mesenteric arteries, PGI 2 (0.01-10 µM) evoked relaxation that was blunted at ≥0.1 µM. Interestingly, such relaxation to PGI 2 was increased in TP −/− /EP3 −/− vessels but unaltered in those of EP3 −/− mice ( Figure 4B).…”

“…TP −/− , EP3 −/− , and TP −/− /EP3 −/− mice (on a C57BL/6 background) were produced as described previously. 15,17,29,30 Genotyping of TP −/− was performed by digesting tail biopsy PCR products with a restriction enzyme Bcnl (Thermo Fisher Scientific, Carlsbad, CA), which yielded fragments of 318 and 168 bp or those of 219, 168, and 121 bp in TP −/− or WT mice, respectively (Supporting Figure S1; upper). PCR primers for TP −/− genotyping were 5′-GAA AGG GTA TTT TGT TCC TGA GGC-3′ (sense) and 5′-GCT ACC CCC ATG AAG TAG CAC AGG-3′ (antisense).…”

“…The in vitro kidney perfusion was performed as described previously. 30 Briefly, mice were heparinized (1,000U/kg, i.p.) 20 minutes before they had been anesthetized with pentobarbital (100 mg/kg, i.p.).…”

“…15,19 Interestingly, the expression of EP3 has been found to vary considerably among vascular beds. 29,30 Moreover, vessels that contract to low concentrations of PGI 2 , such as renal arteries and abdominal aorta, show a common property in having a substantial expression or functional presence of EP3. 15,19,29,30 Thus, its higher potency on EP3 than on TP could be a reason for PGI 2 's evoking vasoconstrictor activity at low concentrations in these vessels.…”