AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 3 364-R368, Copyright © 1984 by American Physiological Society
PAH excretion in two species of cancroid crab Cancer irroratus and C. borealis
C. W. Holliday and D. S. Miller
To determine the characteristics of p-aminohippuric acid (PAH) excretion in
Cancer irroratus and C. borealis, crabs were given a single injection of
radiolabeled PAH and polyethylene glycol (PEG), and serum, urine, tissue,
and seawater concentrations of each were measured over the next 6 days. In
both species, PEG clearances averaged 5-10 ml serum/day; serum PAH
concentrations fell exponentially after a 1-day equilibration period. In C.
irroratus, urine PAH rose over the first 2 days and then fell; during days
2-6, mean urine PAH averaged two to four times mean serum PAH. In C.
borealis, urine-to-serum ratios for PAH were 20-40 during days 2-6.
PAH-to-PEG clearance ratios exceeded unity in both species, with ratios in
C. borealis about three to six times those in C. irroratus. Tissue
distribution data showed that C. irroratus midgut gland accumulated up to
50% of injected PAH, with gland-to-serum concentration ratios of 15-45; in
this species, stomach fluid-to-serum PAH concentration ratios averaged 87,
and nonurinary routes accounted for more than half of excreted PAH. In C.
borealis, midgut gland-to-serum ratios never exceeded 2, and the urinary
routes accounted for all excreted PAH. Thus, in C. irroratus, injected PAH
accumulated in the midgut gland, with slow excretion through renal and
nonrenal routes; in C. borealis, PAH remained in hemolymph, and only the
renal route of excretion was utilized.
