Roles of CO2, O2, and acid in arteriovenous [H+] difference during muscle contractions.
To determine the origins of the arteriovenous [H+] difference of muscle during contractions, arterial and muscle venous blood sample pairs were taken before and after 0.5, 5.0, and 30.0 min of 4/s isometric twitches of the gastrocnemius-plantaris muscle group of anesthetized dogs. These samples were analyzed for PO2, PCO2, and pH, the concentrations of O2, CO2, K+, Na+, La-, and Cl- in whole blood, and La-, K+, Na+, and Cl- in plasma. Whole blood was hemolyzed and analyzed for PO2, PCO2, and pH. Net O2 uptake, CO2 output, L, K+, Na+, and Cl- were calculated in addition to net output of non-CO2 acid (HA) and strong ion difference ([SID]) and common ion [SID] ([K+] + [Na+] - [Cl-] - [La-]). From these data we partitioned the origins of the arteriovenous [H+] difference via the common PCO2-pH diagram and via a [H+]-PCO2 diagram and determined whether true plasma arteriovenous [H+] differences reflect plasma and cell arteriovenous [H+] differences. The arteriovenous [H+] differences of plasma and hemolyzed blood were the same, showing that true plasma does reflect plasma and cells. K+ showed a small significant but transient output. Na+ was not significant, whereas Cl- showed a significant transient uptake. Lactate output and HA, calculated for dog blood acid-base, showed transient outputs and were the same. At 5.0 min when the arteriovenous difference was largest, CO2 alone would have increased [H+] 15.9 nmol/l whereas desaturation of Hb would have decreased [H+] 4.2 nmol/l and lactate could have raised [H+] 1.0 nmol/l.(ABSTRACT TRUNCATED AT 250 WORDS)
Stainsby
W N
WN
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610.
Eitzman
P D
PD
D000136:Acid-Base Equilibrium; D000818:Animals; D000838:Anions; D001158:Arteries; D002245:Carbon Dioxide / Q000097:blood*; D002412:Cations; D002712:Chlorides / Q000097:blood; D004285:Dogs; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D009119:Muscle Contraction; D009132:Muscles / Q000098:blood supply*; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010949:Plasma / Q000378:metabolism; D011188:Potassium / Q000097:blood; D011522:Protons; D012964:Sodium / Q000097:blood; D014680:Veins
D000838:Anions; D002412:Cations; D002712:Chlorides; D007773:Lactates; D011522:Protons; D002245:Carbon Dioxide; D019344:Lactic Acid; D012964:Sodium; D011188:Potassium; D010100:Oxygen