title: Effects of temperature on muscle pHi and phosphate metabolites in newts and lungless salamanders.
abstract: The effect of acute alterations in body temperature (BT) on intracellular pH (pHi) and phosphate metabolites was assessed in white skeletal muscle of intact newts and lungless red-backed salamanders using 31P-nuclear magnetic resonance spectroscopy. pHi decreased with increasing BT in the tail muscle of both newts and lungless red-backed salamanders. The change in pH with change in temperature from 10 to 30 degrees C was -0.018 U/degrees C in newts and -0.041 U/degrees C in red backs. The calculated alpha-imidazole for skeletal muscle cytosol did not change (0.56) in newts from 10 to 30 degrees C but fell from 0.69 to 0.43 in red-backed salamanders. Phosphocreatine (PCr)/Pi fell and Pi/beta-ATP rose with increasing temperature in both newts and red backs; however, the change was much greater in red backs. Providing the red backs with O2 at 30 degrees C led to higher pH and alpha-imidazole, comparable to that of newts, along with increased PCr/Pi and lower Pi/beta-ATP. Thus newts maintain white skeletal muscle cell cytosol alpha-imidazole constant with changes in BT, whereas red backs apparently do not. However, at the BT of preference, red backs and newts maintain similar muscle pHi and alpha-imidazole. The method of gas exchange appears to strongly influence the ability of an animal to maintain its acid-base status over a range of temperatures, and our results suggest that behavioral regulation of BT may involve alpha-imidazole regulation as well.
authors.affiliation: Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
authors.forename: D C
authors.initials: DC
authors.lastname: Johnson
authors.forename: C T
authors.initials: CT
authors.lastname: Burt
authors.forename: W C
authors.initials: WC
authors.lastname: Perng
authors.forename: B M
authors.initials: BM
authors.lastname: Hitzig
mesh_terms: D000064:Acclimatization; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004734:Energy Metabolism; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009132:Muscles / Q000378:metabolism / Q000502:physiology*; D009673:Notophthalmus viridescens / Q000502:physiology*; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D012455:Salamandridae / Q000502:physiology*; D013045:Species Specificity; D013696:Temperature
chemical_list: D010710:Phosphates; D010725:Phosphocreatine; D000255:Adenosine Triphosphate