pH control in rat skeletal muscle during exercise, recovery from exercise, and acute respiratory acidosis.
We used 31P magnetic resonance spectroscopy to compare the response of rat skeletal muscle to three kinds of proton load. During exercise (tetanic sciatic nerve stimulation), protons from lactic acid were buffered passively and consumed by net hydrolysis of phosphocreatine (PCr). During recovery from exercise, the pH-dependent efflux of protons produced by PCr resynthesis could be partially inhibited by amiloride or 4,4'-diisothiocyanostilbene-2,2'-disulphonate (DIDS), implicating both sodium/proton and bicarbonate/chloride exchange, but was not inhibited by simultaneous respiratory acidosis. In early recovery, up to 30% of proton efflux was mediated by lactate/proton cotransport. During acute respiratory acidosis at rest, the eventual change in muscle pH was consistent with passive buffering and was unaffected by amiloride or DIDS, implying no significant contribution of proton fluxes.
Kemp
G J
GJ
MRC Biochemical and Clinical Magnetic Resonance Unit, John Radcliffe Hospital, Oxford, United Kingdom.
Thompson
C H
CH
Sanderson
A L
AL
Radda
G K
GK
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000142:Acidosis, Respiratory / Q000097:blood / Q000378:metabolism / Q000503:physiopathology*; D000208:Acute Disease; D000244:Adenosine Diphosphate / Q000378:metabolism; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002021:Buffers; D002245:Carbon Dioxide / Q000097:blood; D002254:Carbonates / Q000378:metabolism; D004558:Electric Stimulation; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000096:biosynthesis; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012146:Rest / Q000502:physiology; D012584:Sciatic Nerve / Q000502:physiology
D002021:Buffers; D002254:Carbonates; D007773:Lactates; D010725:Phosphocreatine; D002245:Carbon Dioxide; D010758:Phosphorus; D019344:Lactic Acid; D000244:Adenosine Diphosphate; D000584:Amiloride; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid