CYCLOSPORINE-A MODULATION OF CA++ ACTIVATED K+ CHANNELS IN CARDIAC SENSORY AFFERENT NEURONS

Whole-cell and single channel recordings were used to characterize the effects of the immunosuppressant cyclosporine A (CsA) on cardiac sens ory neurons (CSN) of the nodose ganglia. Application of 10 nM CsA resu lted in a 29.1% decrease in CSN input resistance and an average -8 +/- 3 mV hyperpolarization of membrane potential. Application of 10 nM Cs A had no effect on evoked Ca++ currents but increased evoked K+ curren ts by 158.9 +/- 24%. Application of 10 nM CsA significantly increased the open probability of KCa channels by 183 +/- 9%. These results sugg est that application of CsA results in the activation of KCa channels in cardiac sensory neurons and this effect may contribute to the cellu lar mechanisms underlying CsA modulation of vagal afferent neurons. (C ) 1998 Elsevier Science B.V.