Abstract
Rationale: α-calcitonin gene related peptide (αCGRP), one of the strongest vasodilators, is cardioprotective in hypertension by reducing the elevated blood pressure (BP). Objective: However, we hypothesize that endogenous, physical activity-induced αCGRP has BP-independent cardioprotective effects in chronic hypertension. MMethods and Results: Chronically hypertensive (one-kidney-one-clip surgery) WT 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. BP was similar among all hypertensive experimental groups. Endogenous αCGRP limited pathological remodeling and heart failure in sedentary, chronically hypertensive WT 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 BP-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 hypertensive patients.
Skaria, Tom