Developmental change in the voltage-dependence of the pacemaker current, if, in rat ventricle cells |
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Authors: | RB Robinson H Yu F Chang IS Cohen |
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Affiliation: | Department of Physiology and Biophysics, HSC, SUNY at Stony Brook, Stony Brook, NY, USA. |
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Abstract: | Myocytes were isolated from newborn and adult rat ventricle. Using the whole-cell patch clamp, the two cell populations were compared for the presence of the hyperpolarization-activated pacemaker current if. As in other mammalian species, the threshold voltage in acutely dissociated adult rat myocytes was extremely negative (-113 +/- 5 mV; n=12). In contrast, threshold in newborn cells was relatively positive, regardless of whether measured in acutely dissociated (-72 +/- 2 mV; n=6) or cultured cells (-70 +/- 2 mV; n=9). Current density was not reduced in the adult. These results suggest that with development the ventricle assumes its non-pacemaker function, at least in part, by a shift of the voltage dependence of if outside the physiological range. |
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