Decreased sustained potassium current contributes to different firing patterns of celiac neurons in DOCA‐salt hypertensive and normotensive Rats

Abstract

It is not known if changes in the electrophysiological properties of sympathetic ganglia neurons contribute to increased sympathetic activity in hypertension. Using whole‐cell patch clamp dissociated celiac neurons from hypertensive and normotensive rats were divided into three groups based on their action potential (AP) firing patterns to a constant suprathreshold depolarizing current (100pA; 400 ms). Phasic neurons fired several APs and adapted quickly; tonic‐phasic neurons fired several APs and adapted slowly; tonic neurons fired continuously. The distribution of these three groups was significantly different in neurons from hypertensive rats. There were more phasic neurons, less tonic‐phasic neurons and similar amount of tonic neurons in hypertensive rats. The firing frequency in tonic neurons was higher in hypertensive rats compared to normotensive rats. Potassium channel currents were tested to explore the reason of these neuronal firing changes in hypertension. Sustained potassium current was significantly lower in celiac neurons from hypertensive rats compared to those from normotensive rats. The M‐type and A‐type potassium currents were not different between hypertensive and normotensive rats. In normotensive rats, 23.44mM tetraethylammonium (TEA) reduced the amplitude of sustained potassium currents by 50%. TEA also decreased the firing frequency in tonic neurons and converted tonic‐phasic neurons to phasic neurons. The different celiac neuronal firing patterns contributed by decreased sustained potassium current may play a compensatory role in elevated sympathetic activity in hypertension.Support HL70687