title: Effect of parathyroid hormone on energy metabolism of skeletal muscle.
abstract: Clinical states with primary or secondary hyperparathyroidism are associated with muscle dysfunction, suggesting that parathyroid hormone (PTH) may affect muscle metabolism. The present study examined the effect of 1-84 PTH and its amino-terminal fragment (1-34 PTH) on energy production, transfer, and utilization by skeletal muscle. Rats weighing 150 to 200 g were injected intraperitoneally with 1-84 or 1-34 PTH, 200 U/day, for 4 days, and control animals received vehicle only. The effect of the simultaneous administration of a calcium channel blocker, verapamil, was examined also. The muscle content of inorganic phosphorus, creatine phosphate, and adenine nucleotides were significantly (P less than 0.01) lower in the PTH-treated rats than in control animals. The hormone significantly reduced mitochondrial oxygen consumption without altering ADP:0 ratio, indicating reduced phosphorylation. Both 1-84 and 1-34 PTH produced significant (P less than 0.01) reduction in the activities of mitochondrial and myofibrillar CPK, and mitochondrial MgATPase. 1-84 PTH reduced the activity of myofibrillar CaATPase as well. There was a significant (P less than 0.01) increment in muscle uptake of 45Ca in the 1-84 PTH-treated rats. Verapamil abolished all the effects of PTH. Our data demonstrate that both 1-84 and 1-34 PTH impair energy production, transfer, and utilization. These biochemical derangements may, at least in part, underlie the myopathy observed in conditions associated with excess PTH.
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism; D004734:Energy Metabolism / Q000187:drug effects*; D008931:Mitochondria, Muscle / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D019379:Teriparatide; D014700:Verapamil / Q000494:pharmacology
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010710:Phosphates; D010725:Phosphocreatine; D019379:Teriparatide; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D014700:Verapamil; D003402:Creatine Kinase; D000251:Adenosine Triphosphatases