Microvascular remodelling and expression of VEGF receptors after endurance training with Co²⁺ treatment in the rat myocardium

Abstract

This study was designed to examine the changes in the capillary geometry and expression of VEGF receptors Flt-1(VEGFR-1) and Flk-1/KDR (VEGFR-2) in the left ventricles of female Wistar rats after endurance training with and without chronic CoCl₂ administration. The four groups of rats were non-treated sedentary, non-treated training, Co²⁺-treated sedentary and Co²⁺-treated training groups. Exercise training by running lasted for 5 weeks at 25 m/min on a 20% gradient, 10-60 min/day, 5 days per week. The Co²⁺ -treated rats drank water containing 0.01% CoCl₂ for 5 weeks. The Co²⁺ administration significantly increased the blood hemoglobin concentration by approximately 25% with and without training. In the subendocardium, both Co²⁺-treated groups with and without training significantly increased the capillary-to-myocyte ratio (C:M) whereas training alone did not. Training with Co²⁺ significantly increased the C:M ratio of arteriolar capillary. Although expression of VEGFR-2 protein was increased after Co²⁺ administration (by 59%) and training with Co²⁺ (by 46%), that of VEGFR-1and VEGF remained unchanged. These results suggest that chronic Co²⁺ administration facilitates capillary angiogenesis via VEGF system, but exercise training does not cause angioadaptation in myocardium. [Jpn J Physiol 54 Suppl:S239 (2004)]