Ouabain-resistant hyperpolarization induced by insulin in aggregates of embryonic heart cells.
AUTOR(ES)
Lantz, R C
RESUMO
Spheroidal aggregates formed from trypsin-dissociated 14-day embryonic chicken hearts after 48 hr of rotation on a gyratory shaker. Intracellularly recorded resting membrane potentials of aggregates bathed in 1.3 mM K+ balanced salt solution had a mean (+/- SD) of 64 +/- 4 mV. After a stable potential was achieved, addition of 1-100 nM sodium bovine insulin caused a slow hyperpolarization of up to 19 mV after 4-5 min, followed, in some cases, by a further, more rapid, shift to a potential near EK. Equivalent hyperpolarizations were observed when insulin was added in the presence of 10 mM ouabain, indicating that enhanced Na+,K+ pump activity was not responsible for the change in membrane potential. The concentration of insulin that produced half-maximal hyperpolarization (2 nM) corresponded to the association constant of a high-affinity insulin receptor, suggesting that binding to this class of receptors led to the change in membrane potential. Steady-state current-voltage curves from current clamp experiments suggested that insulin produced an increase in slope conductance at potentials near rest by inducing an outward current with an apparent potential negative to -90 mV.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=349547Documentos Relacionados
- Amplification of DNA sequences coding for the Na,K-ATPase alpha-subunit in ouabain-resistant C+ cells.
- Induction of ouabain-resistant mutations in C3H 10T1/2 mouse cells by ultraviolet light.
- Glucose stimulation of ouabain-resistant efflux of Na+ from rat pancreatic islets.
- Rat-brain Na,K-ATPase beta-chain gene: primary structure, tissue-specific expression, and amplification in ouabain-resistant HeLa C+ cells.
- Induction of Ouabain-resistant Mutation and Sister Chromatid Exchanges in Chinese Hamster Cells with Chemical Carcinogens Mediated by Human Pulmonary Macrophages