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Effect of Ethanol on Function of the Rat Heart and Skeletal Muscles
Author(s) -
Pagala Murali,
Ravindran Kadirimangalam,
Amaladevi Bellamkonda,
Namba Tatsuji,
Grab David
Publication year - 1995
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1995.tb01567.x
Subject(s) - stimulation , skeletal muscle , heart rate , medicine , diaphragm (acoustics) , chemistry , ethanol , phrenic nerve , tetanic stimulation , perfusion , anesthesia , endocrinology , sciatic nerve , anatomy , respiratory system , blood pressure , long term potentiation , biochemistry , physics , receptor , acoustics , loudspeaker
The present study was undertaken to evaluate the acute effects of ethanol on responses of the rat heart and skeletal muscles both in vivo and in vitro. In the anesthetized rat, intravenous infusion of ethanol at 0.1–0.5 g/kg body weight (33–167 m m ) decreased the breathing rate by 8–83%, heart rate by 4–52%, and QRS amplitude by 5–27%, and increased the P‐R interval by 1–49%. In the anterior tibialis muscle subjected to repetitive nerve stimulation at 100 Hz for 0.5 sec, ethanol at 0.1 g/kg increased the amplitude of the muscle action potential (AP) by 7%, whereas at 0.5 g/kg it decreased the muscle AP by 32%. The nerve‐evoked tetanic tension was reduced by 7–34% at 0.1–0.5 g/kg ethanol. In the isolated rat heart, perfusion of ethanol at 0.1–3.0% (22–651 m m ) decreased the heart rate by 8–48% and QRS amplitude by 10–39%, and increased the P‐R interval by 5–61%. Left ventricular pressure was increased by 10% at 0.1 % ethanol, and decreased by 80% at 3.0% ethanol. In the isolated rat phrenic nerve‐diaphragm muscle preparation subjected to repetitive nerve stimulation at 100 Hz for 0.5 sec, 0.1–3.0% ethanol decreased the amplitude of the nerve AP by 5–89%, nerve‐evoked muscle AP by 2–96%, and peak tetanic tension by 1–87%. On repetitive direct muscle stimulation at 100 Hz for 0.5 sec, 0.1–3.0% ethanol decreased the amplitude of the muscle‐evoked muscle AP by 8–65%, and muscle‐evoked tetanic tension by 2–65%. These studies indicate that ethanol causes smaller reduction in responses of the heart and skeletal muscles at clinical concentrations, but marked reduction in these responses at higher concentrations due to direct action on excitability of these tissues. At higher concentrations, ethanol causes greater reduction in excitability of the skeletal muscle than of the heart.