LUTEINIZING HORMONE‐RELEASING FACTOR AND MUSCARINIC AGONISTS ACT ON THE SAME VOLTAGE‐SENSITIVE K+ ‐CURRENT IN BULLFROG SYMPATHETIC NEURONES

Abstract

The effect of bath-applied luteinizing hormone-releasing factor (LHRF) was recorded in voltage-clamped bullfrog lumbar sympathetic neurones. At a holding potential of −30 mV, LHRF induced a steady inward (depolarizing) current and reduced membrane conductance; at −60 mV LHRF produced negligible inward current and much less conductance change. The effects of LHRF were accompanied by a reduced amplitude of the slow current relaxations following hyperpolarizing and depolarizing commands, without prominent change in their time-course. This suggests a selective depression of the voltage-sensitive outward K⁺ -current which is suppressed by muscarinic agonists.