PAH transport in rock crab (Cancer irroratus) urinary bladder.

Autor: Holliday CW, Miller DS
Jazyk: angličtina
Zdroj: The American journal of physiology [Am J Physiol] 1980 May; Vol. 238 (5), pp. R311-7.
DOI: 10.1152/ajpregu.1980.238.5.R311
Abstrakt: Crab urinary bladder appears to possess several morphological and functional similarities to vertebrate renal proximal tubule. Sections of intermolt rock crab bladder accumulated PAH by a process that was concentrative (60 min tissue-to-medium ratio (T/M) for 10 microM PAH averaged 24), Na dependent, powered by glycolytic metabolism, and inhibitable by other organic anions. Initial section uptakes exhibited saturation kinetics and a double-reciprocal plot of uptake vs. concentration yielded a single line with a Km of 70 microM and a Vmax of 5 nmol . mg tissue-1 . h-1. Chlorophenol red and bromocresol green (BCG) competitively inhibited PAH uptake. When bladder sheets were mounted in a flux chamber, they exhibited a large, net lumen-to-serosa (L leads to S) flux of 10 microM PAH that was abolished by 1 mM BCG. The small unidirectional S leads to L flux was not BCG-inhibitable. Bladder sheets exhibited PAH T/M greater than 1 after luminal, but not serosal, exposure. BCG only reduced bladder sheet T/M after luminal exposure. The data are consistent with uphill, Na-dependent, and carrier-mediated entry of PAH at the luminal membrane and nonmediated exit at the serosal membrane.
Databáze: MEDLINE