title: Physiological basis for swimming endurance differences between LDH-B genotypes of Fundulus heteroclitus.
abstract: Adenosine triphosphate levels in erythrocytes are correlated with LDH-B genotype in Fundulus heteroclitus. Adenosine triphosphate is the fish's allosteric modifier of hemoglobin oxygen affinity. Since oxygen delivery to muscle affects swimming performance, fish of each homozygous LDH-B phenotype were swum to exhaustion at 10 degrees or 25 degrees C to determine whether in vitro differences attributed to the LDH-B allelic isozymes were manifest in vivo. At 10 degrees C, the critical swimming speed of the LDH-BaBa phenotype was 3.6 body lengths per second, whereas that of the LDH-BbBb phenotype was 4.3 body lengths per second. At 25 degrees C there were no differences between LDH-B phenotypes in erythrocyte adenosine triphosphate levels, blood oxygen affinity, or swimming performance.
mesh_terms: D000255:Adenosine Triphosphate / Q000097:blood; D000818:Animals; D005399:Fishes / Q000502:physiology*; D005787:Gene Frequency; D007527:Isoenzymes; D007695:Killifishes / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D005082:Physical Exertion; D013550:Swimming; D013696:Temperature
chemical_list: D007527:Isoenzymes; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D010100:Oxygen