Effects of dexmedetomidine on cardiac electrical activity and ion currents: An experimental animal study

Objectives: Dexmedetomidine is a potent and highly selective alpha-2 adrenergic receptor agonist recognized for its sedative, hypnotic, analgesic, and sympatholytic properties. The diverse cardiac and hemodynamic effects of dexmedetomidine have been thoroughly documented. Consequently, we investigated its impact on electrophysiological parameters, including action potential and contraction in ventricular myocytes. Methods: Freshly isolated ventricular myocytes from adult Wistar rats were used for experiments. The contraction and relaxation responses, action potentials, L-type calcium currents, and potassium channel currents of the myocytes were recorded using a video-based contractility system and the whole-cell patch clamp technique. Results: While higher concentrations of dexmedetomidine progressively inhibit the contractile responses of cardiomyocytes, they did not significantly impact the action potential repolarization phase or potassium currents (including both transient outward and inward rectifiers). However, there was a decrease in L-type calcium currents, particularly at potential values ranging from 0 to 30mV. Furthermore, although dexmedetomidine shifted the V50 value toward more positive values in the deactivation-reactivation curve of the L-type calcium channel, no statistically significant difference was observed. Conclusions: Our study demonstrates that dexmedetomidine causes a dose-dependent reduction in contractility and decreases calcium currents. These findings indicate that dexmedetomidine may significantly influence the mechanical and electrical functions of cardiac cells. Additional research is needed to clarify the molecular mechanisms underlying these changes.