Circadian Expression Of Cardiac Connexins And Its Relationship With The Biological Clock

Objective: Significant circadian variations exist in the frequency of cardiac arrhythmia;however,the underlying mechanism is largely unknown.Connexins are essential in the propagation of electrical activity throughout the heart and are an important determinant of conduction velocity.Their dysfunction is related to the genesis of cardiac arrhythmia.Methods: In current study,we investigated if cx40 and cx43 expressed circadianly in the rat heart by using suprachiasmatic nuclei lesion(SCNX)and pharmacological autonomic nervous system block(ANSB)rat.Results: Significant 24-hour variations were observed in the expression of cx40 and cx43 in the sham-operated rats.In the SCNX rat,all genes examined lost circadian rhythm.In the ANSB rat,the expression of Bmal1 was dampened significantly but still had circadian rhythm,whereas the two connexin gene expressions lost rhythm.Conclusion: These results suggest that cx40 and cx43 gene expressions have clear circadian rhythm and might be regulated by the central clock in the SCN through the ANS.