[Selective reduction by morphine and enkephalins of depolarization induced by application of dopamine to Helix pomatia neurons].
Morphine, met-enkephalin and leu-enkephalin (1 . 10(-5)M) rapidly, reversibly and in a naloxone-dependent manner depressed the amplitude of dopamine-induced depolarization in neurons of the snail Helix pomatia. Dopamine hyperpolarization and both types of responses to acetylcholine were not altered by morphine and enkephalins. A hypothesis of Zieglgansberger on a blockade of chemically excitable sodium channels by morphine and enkephalins is discussed. It is suggested that opiates block sodium channels when they are applied in high concentration (1 . 10(-4)-1 . 10(-3)M). Lower concentration of morphine and enkephalins (1 . 10(-5)M) modulate the neurotransmitter postsynaptic responses perhaps by means of affecting the cyclic nucleotide system.
D000109:Acetylcholine / Q000008:administration & dosage; D000818:Animals; D018492:Dopamine Antagonists; D004743:Enkephalin, Leucine / Q000008:administration & dosage; D004744:Enkephalin, Methionine / Q000008:administration & dosage; D004745:Enkephalins / Q000008:administration & dosage*; D005724:Ganglia / Q000187:drug effects*; D006372:Helix, Snails; D066298:In Vitro Techniques; D009020:Morphine / Q000008:administration & dosage*; D009270:Naloxone / Q000008:administration & dosage; D009474:Neurons / Q000187:drug effects
D018492:Dopamine Antagonists; D004745:Enkephalins; D009270:Naloxone; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D009020:Morphine; D000109:Acetylcholine
Izbiratel'noe oslablenie morfinom i énkefalinami depoliarizatsii, vyzvannoĭ applikatsieĭ dofamina na neĭrony vinogradnoĭ ulitki.