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