The direct depressant effect of LCB29 (idrocilamide) on mechanical tension of rat soleus muscle fibers.
The effect of LCB29 was tested on twitch characteristics, tetanic tension, and K+ and voltage-clamp contractures of rat soleus muscle fibers. In concentrations ranging from 10(-6) to 5 x 10(-4) M, LCB29 simultaneously inhibited the twitch amplitude, the maximum rate of tension development, and the maximum rate of relaxation. In concentrations ranging from 10(-5) to 10(-4) M, tetanic tension (100 Hz, 1 s) was inhibited by the same amount. The effect of 5 x 10(-5) M LCB29 was studied on K+ contractures and contractures induced, under voltage-clamp conditions, by long-lasting depolarizations. Its effect was significantly stronger than those on twitch and tetanic tension. In addition, LCB29 had a dual effect on strength--duration curves for mechanical threshold. It increased both the rheobasic potential and the steepness of the curve. It is concluded that LCB29 exerts a direct myorelaxant effect on rat soleus muscle; two sites of action are probably involved.
Bouron
A
A
Laboratoire de physiologie générale, Unité associée au Centre national de la recherche scientifique n. 290, Université de Poitiers, France.
Rivet
M
M
Nasri-Sebdani
M
M
Guillemain
J
J
Durbin
P
P
Guerrier
D
D
Raymond
G
G
D000818:Animals; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D007537:Isometric Contraction; D009119:Muscle Contraction / Q000187:drug effects; D009125:Muscle Relaxants, Central / Q000494:pharmacology*; D009132:Muscles / Q000187:drug effects*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology
D004983:Ethanolamines; D007202:Indicators and Reagents; D009125:Muscle Relaxants, Central; D013779:Tetrodotoxin; C004560:idrocilamide; D011188:Potassium