Effects of monensin on Na+/K+-ATPase and Ca++-ATPase activities in chick skeletal muscle and myocardium after subacute treatment

Chicks were treated at 2 weeks of age with 4, l5, 40, 100 and 150 mg/kg of monensin, an ionophore used for its anticoccidial and growth-promoting properties. In the present immunohistochemical study, the expressions and distribution of Na+/K+- ATPase and Ca++-ATPase were studied in myocardium and skeletal muscles (pectoral and quadriceps femoris). We detected an increase of Na+/K+-ATPase immunostaining with prominent staining of the sarcolemma and a slight increase of Ca++-ATPase with prominent staining of the sarcoplasma.