Role of high-energy phosphates and their metabolites in protection of carbofuran-induced biochemical changes in diaphragm muscle by memantine.

A combined antidotal treatment with memantine HCI (MEM, 18 mg/kg, s.c.) and atropine sulfate (ATS, 16 mg/kg, s.c.) provided complete protection against acute carbofuran toxicity (1.5 mg/kg, s.c.) in rats by multiple mechanisms. Carbofuran, in addition to inhibiting serine-containing esterases, also perturbed the activities of mitochondrial/cytoplasmic biomarker enzymes (creatine kinase, CK; and lactic dehydrogenase, LDH) in diaphragm muscle. The observed changes in the activity of biomarker enzymes were reflected in serum as a result of their leakage from the diaphragm due to a depletion of high-energy phosphates, such as adenosine triphosphate (ATP, 27%) and phosphocreatine (PCr, 33%) and their metabolites (ADP, 36%; AMP, 35%; and Cr, 38%). Combined treatment with MEM and ATS provided protection and reversal of the induced changes in biomarkers by preventing depletion of high-energy phosphates and thus maintaining normal cell membrane characteristics, including permeability and integrity. These results, along with those reported previously, indicate that MEM antagonizes carbofuran toxicity by multiple mechanisms.