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Mechanisms of ammonia and acid extrusion by the little skate,Raja erinacea

✍ Scribed by Evans, David H. ;Kormanik, Gregg A. ;Krasny, Edward J.


Publisher
John Wiley and Sons
Year
1979
Tongue
English
Weight
288 KB
Volume
208
Category
Article
ISSN
0022-104X

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✦ Synopsis


Abstract

The little skate (Raja erinacea) excretes ammonia and titratable acid at a rate of 6.37 and 40–95 ΞΌM. 100g‐1. hr‐1, respectively, at an external pH of 7.8 to 8.0. Transfer into Na‐ and K‐free artifical sea water does not alter the rate of ammonia efflux but reduces titratable acid efflux to zero. Addition of amiloride (10‐4M) to the external sea water does not alter the ammonia efflux but reduces the titratable acid efflux by 49%. Thus, while ammonia efflux is apparently not via Na (or K)/NH4 exchange, excretion of titratable acid is apparently via Na (or K)/H exchange.


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