. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 284 R. W. WISEMAN AND W. R. ELLINGTON. mm FIGURE 4. Distribution of lactate in the incubation media (M) and tissue (Tis) as well as the total (To) lactate produced during electrically induced isotonic contractions of the radula protractor muscles from the whelk Busycon contrarium as determined by fluorometric analysis of neutralized perchloric-acid extracts of each over time. U nits are /imole-g wet wt '. Points represent means ± 1 SD, n = 5. Where error bars are absent, the error bar was less than the size of the symbol use
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 284 R. W. WISEMAN AND W. R. ELLINGTON. mm FIGURE 4. Distribution of lactate in the incubation media (M) and tissue (Tis) as well as the total (To) lactate produced during electrically induced isotonic contractions of the radula protractor muscles from the whelk Busycon contrarium as determined by fluorometric analysis of neutralized perchloric-acid extracts of each over time. U nits are /imole-g wet wt '. Points represent means ± 1 SD, n = 5. Where error bars are absent, the error bar was less than the size of the symbol used to mark points. lively modest accumulation of D-lactate in electrically stimulated preparations of the foot muscle of the cockle Cardium edule. The preferential production of D-lactate versus the opines in B. contrarium radula protractor muscle may be related to a higher binding capacity for pyruvate. The apparent Kms for pyruvate of molluscan LDHs are considerably lower than corresponding Kms of ODHs and somewhat lower than pyruvate Kms for strombine and alanopine dehydrogenases (Gade and Griesha- ber, 1986). Isolated radula muscle preparations of B. contrarium did not release octopine, alanopine, or strombine into the medium. In addition, the total arginine pool (free arginine, arginine phosphate, and octopine) remained constant during contractile activity. The decline in aspartate levels during anoxia probably reflects transdeamina- tion to alanine because, at the end of 15 min, the alanopine-alanine pool size was roughly equivalent to the decrease in aspartate plus initial alanine levels. This conser- vation of nitrogen in both the arginine (arginine, arginine phosphate, octopine) and alanine (alanine, alanopine, aspartate difference) pools is consistent with the observed absence of transport of opine end products out of the muscle. In contrast to that of the opines, release of D-lactate from the muscle was very large. In fact, D-lactate export was greater than D-lactate
Size: 1445px × 1730px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
