CHARACTERISTICS OF THE VENTRICULAR TRANSIENT OUTWARD POTASSIUM CURRENT IN GENETIC RODENT MODELS OF DIABETES

The whole-cell configuration of the patch-clamp technique was employed to measure the transient outward potassium current in enzymatically i solated ventricular cells of spontaneously diabetic rats (BB/Wor) and mice (ob/ob). Healthy littermates (non-diabetic BE rats and lean mice) were used as controls. There was no significant difference between th e non-diabetic and diabetic BE rats (Type I diabetes, IDDM) in the amp litude of either the current measured in the absence or the one found in the presence of 4-aminopyridine. The voltage dependence of the acti vation and steady-state inactivation was also similar in both populati ons, as no significant difference was observed in the rate of recovery from inactivation of I-to. The amplitudes of the total and 4-aminopyr idine sensitive currents of lean and obese mice (Type II diabetes, NID DM) were also similar. The voltage dependences of the activation and o f the steady-state inactivation did not differ significantly, either. Our results might indicate certain limitations of the applicability of experiments carried out on genetically diabetic rats if the results a re compared to those derived from the healthy littermates as controls.