H. Barajas-martinez et al., Developmental differences in delayed rectifying outward current in feline ventricular myocytes, AM J P-HEAR, 278(2), 2000, pp. H484-H492
Citations number
23
Categorie Soggetti
Cardiovascular & Hematology Research
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY
In the present work, we found that the delayed rectifying outward potassium
current (I-K) in adult and neonatal cat ventricular myocytes consists of b
oth rapid and slow components, I-Kr and I-Ks, respectively, which can be is
olated pharmacologically. Thus after complete blockade of I-Kr with dofetil
ide, the remaining I-Ks current is homogeneous, as shown by an envelope of
tails test. I-Kr maximum tail current density, measured at -40 mV, was simi
lar in adult and neonatal myocytes. I-Ks maximum tail current density in ne
onatal myocytes, measured at -40 mV, was significantly smaller than in adul
t myocytes. Activation kinetics of I-Kr and I-Ks was similar in both age gr
oups. However, the I-Kr deactivation time course was significantly faster i
n neonatal than in adult myocytes. Developmental differences in the subunit
composition of I-Kr that display distinctly different deactivation kinetic
s are suggested.