Accession Number : AD0414065

Title :   FACTORS MODIFYING THE ACTION OF NEUROMUSCULAR BLOCKING AGENTS.

Descriptive Note : Final technical rept. 1 Apr 62-31 Mar 63,

Corporate Author : HAMMERSMITH HOSPITAL LONDON (ENGLAND)

Personal Author(s) : Payne,J.P.

Report Date : 31 MAR 1963

Pagination or Media Count : 6

Abstract : The effect of pH on the action of a number of neuromuscular blocking agents has been studied in vitro by means of the frog rectus abdominis muscle and the rat diaphragm. Three different buffering mechanisms were used to change the pH. The most satisfactory results were obtained with tris (hydroxy methyl) amino methane hydrochloride (THAM). A serine - NaOH buffer was effective over a smaller pH range and carbon dioxide al though effective enough in changing the pH had also a restricted range athermore had a specific depressant effect on muscle activity. It was shown that an increase in pH over the range 6.5 to 9.0 improved the response of the frog rectus to acetylcholine. A similar im proved contracture was obtained under the same circumstances with suxamethonium and decame thonium. The blocking action of tubocurarine was shown to be enhanced when the pH was raised to 8.5 and above that of gallamine was reduced. No obvious explanation for this difference was found nor was there any explanation for the absence of change below pH 8.5. The blocking action of suxamethonium and decamethonium was modified in a more complex fashion. With both drugs enhancement and inhibition occurred when tested against acetylcholine. However, whatever the effect the action of acetylcholine was always greatest around a pH of 8.0. No signif icant effect was observed with the other drugs studied. (Author)

Descriptors :   (*CNS DEPRESSANTS, PHYSIOLOGY), PH FACTOR, MUSCLES, DRUGS, NERVOUS SYSTEM, CONTRACTION.

Distribution Statement : APPROVED FOR PUBLIC RELEASE