In:
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 294, No. 3 ( 2008-03), p. R1033-R1043
Abstract:
Posterior isolated gills of Neohelice ( Chasmagnathus) granulatus were symmetrically perfused with hemolymph-like saline of varying [HCO 3 − ] and pH. Elevating [HCO 3 − ] in the saline from 2.5 to 12.5 mmol/l (pH 7.75 in both cases) induced a significant increase in the transepithelial potential difference ( V te ), a measure of ion transport. The elevation in [HCO 3 − ] also induced a switch from acid secretion (−43.7 ± 22.5 μequiv·kg −1 ·h −1 ) in controls to base secretion (84.7 ± 14.4 μequiv·kg −1 ·h −1 ). The HCO 3 − -induced V te increase was inhibited by basolateral acetazolamide (200 μmol/l), amiloride (1 mmol/l), and ouabain (5 mmol/l) but not by bafilomycin (100 nmol/l). The V te response to HCO 3 − did not take place in Cl − -free conditions; however, it was unaffected by apical SITS (2 mmol/l) or DIDS (1 mmol/l). A decrease in pH from 7.75 to 7.45 pH units in the perfusate also induced a significant increase in V te , which was matched by a net increase in acid secretion of 67.8 ± 18.4 μequiv kg −1 h −1 . This stimulation was sensitive to basolateral acetazolamide, bafilomycin, DIDS, and Na + -free conditions, but it still took place in Cl − -free saline. Therefore, the cellular response to low pH is different from the HCO 3 − -stimulated response. We also report V-H + -ATPase- and Na + -K + -ATPase-like immunoreactivity in gill sections for the first time in this crab. Our results suggest that carbonic anhydrase (CA), basolateral Na + /H + exchangers and Na + -K + -ATPase and apical anion exchangers participate in the HCO 3 − -stimulated response, while CA, apical V-H + -ATPase and basolateral HCO 3 − -dependent cotransporters mediate the response to low pH.
Type of Medium:
Online Resource
ISSN:
0363-6119
,
1522-1490
DOI:
10.1152/ajpregu.00516.2007
Language:
English
Publisher:
American Physiological Society
Publication Date:
2008
detail.hit.zdb_id:
1477297-8
SSG:
12
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