TY - JOUR
T1 - Veratridine-induced oscillations in membrane potential of cultured rat skeletal muscle
T2 - Role of the Na-K pump
AU - Brodie, Chaya
AU - Sampson, S. R.
PY - 1990/6
Y1 - 1990/6
N2 - 1. The acute effects of veratridine on membrane potential (Em) and Na-K pump activity in cultured skeletal muscle were examined. 2. At a concentration of 10-4M, veratridine caused depolarization of Em and a decrease in Na-K pump activity. At concentrations of 10-5 and 10-6M, veratridine caused oscillations of Em and an increase in Na-K pump activity compared to untreated, control cells. The oscillations consisted of depolarization to about -40 mV followed by hyperpolarization to about -90 mV; the level of hyperpolarization was higher at 37 than at 23°C. 3. Veratridine-induced oscillations could be prevented by pretreatment with tetrodotoxin (10-6M) and blocked or prevented by ouabain, which depolarizes Em of cultured myotubes. In contrast, depolarization of Em to -60 mV by excess K+ did not alter the amplitude or frequency of the oscillations. 4. The results demonstrate that veratridine-induced increase in Na influx both depolarizes cultured myotubes and increases the activity of the Na-K pump, which repolarizes Em to levels higher than control. This sequence accounts for veratridine-induced oscillations in Em. High concentrations of veratridine cause only depolarization of Em and inhibition of Na-K pump activity.
AB - 1. The acute effects of veratridine on membrane potential (Em) and Na-K pump activity in cultured skeletal muscle were examined. 2. At a concentration of 10-4M, veratridine caused depolarization of Em and a decrease in Na-K pump activity. At concentrations of 10-5 and 10-6M, veratridine caused oscillations of Em and an increase in Na-K pump activity compared to untreated, control cells. The oscillations consisted of depolarization to about -40 mV followed by hyperpolarization to about -90 mV; the level of hyperpolarization was higher at 37 than at 23°C. 3. Veratridine-induced oscillations could be prevented by pretreatment with tetrodotoxin (10-6M) and blocked or prevented by ouabain, which depolarizes Em of cultured myotubes. In contrast, depolarization of Em to -60 mV by excess K+ did not alter the amplitude or frequency of the oscillations. 4. The results demonstrate that veratridine-induced increase in Na influx both depolarizes cultured myotubes and increases the activity of the Na-K pump, which repolarizes Em to levels higher than control. This sequence accounts for veratridine-induced oscillations in Em. High concentrations of veratridine cause only depolarization of Em and inhibition of Na-K pump activity.
KW - Na-K pump
KW - Rb uptake
KW - electrogenic Na-K pump
KW - membrane potential
KW - veratridine
UR - http://www.scopus.com/inward/record.url?scp=0024989079&partnerID=8YFLogxK
U2 - 10.1007/BF00734575
DO - 10.1007/BF00734575
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C2 - 2163752
AN - SCOPUS:0024989079
SN - 0272-4340
VL - 10
SP - 217
EP - 226
JO - Cellular and Molecular Neurobiology
JF - Cellular and Molecular Neurobiology
IS - 2
ER -