Developmental change in the voltage-dependence of the pacemaker current, if, in rat ventricle cells.
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.
Robinson
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RB
Department of Physiology and Biophysics, HSC, SUNY at Stony Brook, Stony Brook, NY, USA.
Yu
H
H
Chang
F
F
Cohen
I S
IS
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development*; D001683:Biological Clocks / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D016276:Ventricular Function