The deleterious role of the prostaglandin E2 EP3 receptor in angiotensin II hypertension.

Angiotensin II (ANG II) plays a key role in regulating blood pressure and inflammation. Prostaglandin E2 (PGE2) signals through four different G protein-coupled receptors, eliciting a variety of effects. We reported that activation of the EP3 receptor reduces cardiac contractility. More recently, we have shown that overexpression of the EP4 receptor is protective in a mouse myocardial infarction model. We hypothesize in this study that the relative abundance of EP3 and EP4 receptors is a major determinant of end-organ damage in the diseased heart. Thus EP3 is detrimental to cardiac function and promotes inflammation, whereas antagonism of the EP3 receptor is protective in an ANG II hypertension (HTN) model. To test our hypothesis, male 10- to 12-wk-old C57BL/6 mice were anesthetized with isoflurane and osmotic minipumps containing ANG II were implanted subcutaneously for 2 wk. We found that antagonism of the EP3 receptor using L798,106 significantly attenuated the increase in blood pressure with ANG II infusion. Moreover, antagonism of the EP3 receptor prevented a decline in cardiac function after ANG II treatment. We also found that 10- to 12-wk-old EP3-transgenic mice, which overexpress EP3 in the cardiomyocytes, have worsened cardiac function. In conclusion, activation or overexpression of EP3 exacerbates end-organ damage in ANG II HTN. In contrast, antagonism of the EP3 receptor is beneficial and reduces cardiac dysfunction, inflammation, and HTN. [ABSTRACT FROM AUTHOR]