Blood Pressure Normalization–Independent Cardioprotective Effects of Endogenous, Physical Activity–Induced αCGRP (α Calcitonin Gene-Related Peptide) in Chronically Hypertensive Mice

Abstract

Rationale: αCGRP (α calcitonin gene-related peptide), one of the strongest vasodilators, is cardioprotective in hypertension by reducing the elevated blood pressure. Objective: However, we hypothesize that endogenous, physical activity–induced αCGRP has blood pressure–independent cardioprotective effects in chronic hypertension. Methods and Results: Chronically hypertensive (one-kidney-one-clip surgery) wild-type and αCGRP −/− sedentary or voluntary wheel running mice were treated with vehicle, αCGRP, or the αCGRP receptor antagonist CGRP8-37. Cardiac function and myocardial phenotype were evaluated echocardiographically and by molecular, cellular, and histological analysis, respectively. Blood pressure was similar among all hypertensive experimental groups. Endogenous αCGRP limited pathological remodeling and heart failure in sedentary, chronically hypertensive wild-type mice. In these mice, voluntary wheel running significantly improved myocardial phenotype and function, which was abolished by CGRP8-37 treatment. In αCGRP −/− mice, αCGRP treatment, in contrast to voluntary wheel running, improved myocardial phenotype and function. Specific inhibition of proliferation and myofibroblast differentiation of primary, murine cardiac fibroblasts by αCGRP suggests involvement of these cells in αCGRP-dependent blunting of pathological cardiac remodeling. Conclusions: Endogenous, physical activity–induced αCGRP has blood pressure–independent cardioprotective effects and is crucial for maintaining cardiac function in chronic hypertension. Consequently, inhibiting endogenous αCGRP signaling, as currently approved for migraine prophylaxis, could endanger patients with hypertension.