Age-related changes in gap junctional protein of the rat heart.

OBJECTIVE: Connexin 43 (Cx43), a membrane protein involved in the control of cell-to-cell communication, is thought to play a role in physiological processes such as tissue homeostasis, growth regulation and development. The aim of the present study was to investigate the change of Cx43 expression in aged myocardium. METHODS AND
RESULTS: Sixteen male Sprague-Dawley rats (adult: 10 weeks old, n=8; aged: two years old, n=8) were used in the present study. In an isolated rat heart Langendorff model, hearts were perfused for 10 min with a modified Krebs-Henseleit bicarbonate buffer. Contractile functions were measured and all hearts were stained with anti-Cx43 antibody for fluorescence microscopic examinations. There were no significant differences observed in heart rate (234+/-8.2 beats/min versus 231+/-15.6 beats/min), left ventricular developed pressure (112.5+/-6.3 mmHg versus 107.2+/-2.5 mmHg), first derivative of the left ventricular pressure (1450.4+/-165.1 mmHg/s versus 1384.6+/-95.4 mmHg/s) and coronary flow (17.4+/-0.7 mL/min versus 21.3+/-1.8 mL/min) between adult and aged rats, respectively. However, significant differences were observed in left ventricular weight (adult versus aged; 0.639+/-0.108 g versus 1.124+/-0.257 g, P=0.04) and in fluorescence examinations where there was reduced distribution of Cx43 in aged myocardium compared with adult myocardium.
CONCLUSIONS: These results demonstrated that the role of Cx43 may be more important than previously reported, and that this protein is partially responsible for the maintenance of cellular structure in myocardial development.