Atrial natriuretic polypeptide hormones induce membrane potential responses in cultured rat glioma cells

Atrial natriuretic hormones (ANHs) applied to polyploid rat glioma cells induced hyperpolarizations of about 30 s duration, followed by depolarizations lasting 1–2 min. Repeated applications of the peptide resulted in desensitization. The reversal potential of −87 mV at an extracellular K + concentration of 5 mM and the decrease of membrane resistance during the hyperpolarization indicate that K + channels were activated by ANH. In these cells the fluorescence signal of 2-[(2-bis[car☐ymethyl]amino-5-methylphenoxy)-methyl]-6-methoxy-8-bis[car☐ymethyl]aminoquinoline (quin2) was not affected by ANH suggesting that ANH did not change the cytosolic Ca 2+-activity.