In:
American Journal of Physiology-Renal Physiology, American Physiological Society, Vol. 275, No. 1 ( 1998-07-01), p. F111-F118
Abstract:
In the rat cortical collecting duct (CCD), epinephrine inhibits vasopressin (AVP)-dependent water permeability and Na + reabsorption. Although inhibition is reversed by the α 2 -adrenoceptor (AR) antagonist yohimbine, suggesting the epinephrine effect is primarily mediated by an α 2 -AR [C. T. Hawk, L. H. Kudo, A. J. Rouch, and J. A. Schafer. Am. J. Physiol. 265 ( Renal Fluid Electrolyte Physiol. 34): F449–F460, 1993], there are also suggestions of an effect at an additional receptor, perhaps an α 1 -AR. For the present experiments, we used RT-PCR of total RNA extracted from 1 to 5 mm of microdissected CCDs from rat kidney to identify the α-AR isoforms expressed. Specific primers for the α 2 -ARs amplifying from the 6th transmembrane (TM) to the 3′-untranslated regions, revealed the presence of α 2A and α 2B . Western blot analysis also indicated the presence of α 2B -AR at the protein level. Degenerate α 1 -AR primers that amplify from conserved regions of TM-1 to TM-5, as well as specific primers that amplify either the same region (α 1B ), the carboxy terminus (α 1A ), or within the third cytoplasmic loop (α 1D ), indicated the presence of all three α 1 -ARs. Measurement of transepithelial voltage in isolated perfused renal tubules indicated a small inhibitory effect mediated by α 1 -ARs. Although the functional effects of epinephrine on AVP-dependent transport processes appear to be mediated predominantly by an α 2 -AR, a small contribution to the overall α-AR effect may be due to simultaneous activation of an α 1 -AR.
Type of Medium:
Online Resource
ISSN:
1931-857X
,
1522-1466
DOI:
10.1152/ajprenal.1998.275.1.F111
Language:
English
Publisher:
American Physiological Society
Publication Date:
1998
detail.hit.zdb_id:
1477287-5
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