Increased Cx43 and Angiogenesis in Exercised Mouse Hearts

Abstract

Several studies focused on the macroscopic architecture of increased cardiac wall induced by exercise training. Our goal was to evaluate myocardiocyte, interstitial and vascular component, and connexin-43 expression in endurance-trained mouse hearts. Sixty-three 10-week-old male Swiss mice were divided into four sedentary groups (C0, C15, C30 and C45) and three groups exercised respectively for 15 (T15-D; running intensity [RI]: 3.18 m/min; running duration [RD]: 75 min/first week and 150 min/second week), 30 (T30-D; RI: 3.96 m/min; RD: 150 min/third week and 225 min/fourth week) and 45 days (T45-D; RI: 3.96 m/min and 4.8 m/min, respectively for the fifth and sixth week; RD: 300 min) on a treadmill. Morphometric analyses were performed to quantify myocardiocyte size and number, and the capillary and interstitial connective tissue (ICT) area. We assessed the expression of ventricle myosin light chain-II, vimentin and connexin-43 by western blot analyses. Our results showed a hypertrophy of the interventricular septum and left ventricle in T30-D and T45-D mice that was not due to variations in myofibrillar content, myocardiocyte size and number, or ICT quantity but to a significant increase in the capillary area. The microvascular remodeling was associated with vimentin increased expression in ICT cells and connexin-43 upregulation. The first phenomenon might be related to an enhanced request of remodeling and growth factors; the second suggests a new role of connexin-43 in cardiac angiogenesis.

Late cardioprotection of exercise preconditioning against exhaustive exercise-induced myocardial injury by up-regulatation of connexin 43 expression in rat hearts

“…And a higher Cx43 protein level was found in the group LEP + EE than in the group EE. Bellafiore et al also reported similar results, and they found there is a progressive increase of Cx43 expression levels in response to endurance training that reached a peak in ventricular myocardium of mice exercised for 30 d [19].…”

“…Considering the same powerful cardioprotective effects of both EP and IP as well as the key role of increased expression of Cx43 in IP cardioprotection, we hypothesized that Cx43 may involve in cardioprotective signaling transduction of EP. It has been observed that endurance exercise training preserves a higher expression level of Cx43 in heart under resting conditions [19] . Moreover, the expression level of Cx43 is down-regulated in trained mice during acute exercise [20].…”

Temporal changes in expression of connexin 43 after load-induced hypertrophy in vitro

“…Kostin and colleagues (26) showed that the upregulation of Cx43 was detected in compensated (EF Ͼ 50%) cardiac hypertrophy. An increase in Cx43 expression was also found in exercise-trained mouse hypertrophied hearts (9). On the other hand, a decrease in Cx43 was detected in decompensated (EF Ͻ 30%) hypertrophied hearts, a result similar to those detected in heart failure patients (16,34,42).…”

Connexin 43 expression at an early stage in dog mandibles by β-TCP

“…Concerning to the role of tissue repairing by β-TCP, it has been reported that Cx43 has a novel role in modulating wound healing in fibrotic scar tissue and plays a role in the regeneration of cardiac muscle after tissue injury 21) . Interestingly, microvascular remodeling was associated with Cx43 upregulation 22) . Moreover, Cx43 deficiency in mice causes the dysregulation of coronary vasculogenesis.…”