Demonstration of a voltage dependent calcium current in follicles of the cockroach Nauphoeta cinerea |
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Authors: | ERWIN SIGEL ROLAND BAUR JOSEPH G. KUNKEL HELMUT KINDLE BEATRICE LANZREIN |
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Affiliation: | 1. Institute of Pharmacology, University of Berne , Friedbühlstrasse 49, CH-3010, Berne, Switzerland;2. Division of Animal Physiology , Erlachstrasse 9a, CH-3012, Berne |
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Abstract: | Summary The electrical properties of vitellogenic cockroach follicles have been studied using a two-electrode voltage-clamp technique. The resting potential of freshly isolated follicles was usually between ?30 mV and ?45 mV. A voltage-dependent inward current could be activated when the follicles were placed in a medium containing high concentrations of either Ca2+ or Ba2+. Maximal current amplitudes were 0.8μA in a medium containing 30 mM Ca2+ and 2 μA in 30 mM Ba2+. Maximal amplitudes could be elicited with depolarizing pulses to about +15 mV. The steady-state inactivation curve indicated half maximal current at a holding potential of about ?20 mV. Co2+, Ni2+ and Mn2+ inhibited the divalent cation currents in a concentration dependent manner. Half maximal inhibition was observed at about 3 mM concentration for each of the inhibitory cations. |
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Keywords: | ion current calcium follicle cockroach |
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