title: The influence of catecholamines on Na, K transport in slow- and fast-twitch muscles of the rat.
abstract: The effects of catecholamines on active sodium and potassium transport was compared in slow- (SOL) and fast-twitch (EDL) skeletal muscles of the rat. Stimulation of active Na+-extrusion and K+-uptake induced by adrenaline (6-30 mumol . l-1) and isoprenaline (1-40 mumol . l-1) was markedly greater in slow- than in fast-twitch muscle. In sodium-preloaded muscles the maximal stimulation of 24Na-efflux induced by adrenaline was about 2-fold higher in SOL than in EDL. Isoprenaline caused a 2.4-fold increase in ouabain-sensitive 86Rb influx in SOL muscle, but failed to alter the ouabain-sensitive influx in EDL. The stimulating action of isoprenaline on 86Rb influx in EDL was due to an increase in the ouabain-insensitive fraction of Rb uptake. The effects of catecholamines of fast- and slow-twitch muscles were probably due to the accumulation of cyclic AMP, however the fact that there were no significant differences between the nucleotides levels in fast- and slow-twitch muscle suggests the participation of other mechanism as well. The results presented suggest that cyclic AMP-induced stimulation of ouabain-insensitive transport of cation in the isolated EDL muscle of the rat is similar to that of barnacle muscle.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D009132:Muscles / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000378:metabolism*
chemical_list: D010042:Ouabain; D003994:Bucladesine; D012964:Sodium; D007545:Isoproterenol; D011188:Potassium; D004837:Epinephrine