Accession Number : AD0715527

Title :   Facilitatory Drug Action on the Isolated Phrenic Nerve-Diaphragm Preparation of the Rat,

Corporate Author : DEFENCE STANDARDS LABS MARIBYRNONG (AUSTRALIA)

Personal Author(s) : Freeman,Shirley E. ; Turner,R. J.

Report Date : 10 MAY 1970

Pagination or Media Count : 11

Abstract : The action of facilitatory drugs was studied in the phrenic nerve-diaphragm preparation and the chronically denervated diaphragm of the rat. The latter was used as a model of the post-synaptic receptor. The drugs were tetrahydro-4-aminoacridine and a series of hydroxy-anilinium compounds which included endrophonium. The drugs caused twitch potentiation and spontaneous activity in the intact preparation; these effects were depressed by temperature reduction, low Ca(++) solutions or high Mg(++) solutions. The acetylcholine contraction of the denervated diaphragm was potentiated by all drugs except 3-hydroxyphenyl-triethylammonium. The acetylcholine depolarization was similarly affected. This potentiation was suppressed by raised levels of Ca(++) or Mg(++). Interactions between the facilitatory drugs and succinylcholine are described. Succinylcholine abolished twitch potentiation of the intact preparation at low concentrations; only 3-hydroxyphenyldiethylmethylammonium proved to be an effective antagonist of succinylcholine blockade. Facilitation in the intact junction appears to be largely a presynaptic effect. (Author)

Descriptors :   (*DRUGS, *NEUROMUSCULAR TRANSMISSION), (*DIAPHRAGMS(ANATOMY), DRUGS), NERVOUS SYSTEM, NERVES, AMMONIUM COMPOUNDS, ACRIDINES, AMINES, EFFECTIVENESS, DOSAGE, RESPONSE(BIOLOGY), MUSCLES, CONTRACTION, RATS, PHYSIOLOGY, CALCIUM, MAGNESIUM, IONS

Subject Categories : Pharmacology

Distribution Statement : APPROVED FOR PUBLIC RELEASE