Glomerular and tubular alpha 1- and alpha 2-adrenoceptors in the rat kidney: distribution in basolateral and brush border membranes of tubular cells.
Rat kidney glomeruli and cortical tubules were obtained by a combination of sieving and differential centrifugation technique. [3H]Prazosin and [3H]rauwolscine were used to identify and quantify the alpha 1- and alpha 2-adrenergic receptors, respectively. In the glomeruli, the alpha 1-adrenoceptor concentration was 27% and alpha 2-adrenoceptor concentration was 33% of the corresponding values in the tubules. Further localization of the tubular alpha-adrenoceptors was undertaken by studies in the isolated basolateral membrane and comparison with values in the crude plasma membrane. alpha 1-Adrenoceptors were enriched 1.54 +/- 0.1 times and alpha 2-adrenoceptors were enriched 1.73 +/- 0.04 times in the basolateral membrane as compared to crude plasma membrane. However, these values were significantly (p less than 0.05) less than the enrichment value of 2.77 +/- 0.3 obtained for the basolateral membrane marker (Na+ + K+)-ATPase. These results suggested the possibility that alpha 1- and alpha 2-adrenoceptors may also be distributed in the brush border membrane. Direct-binding studies in the purified renal brush border membrane indicated alpha 1-adrenoceptor concentration of 82.1 +/- 3.8 and alpha 2-adrenoceptor concentration of 108.2 +/- 9.3 fmol/mg protein. These values were 32 and 17% of the corresponding values in the basolateral membrane. Overall, our results suggest that alpha 1- and alpha 2-adrenoceptors are present both in the basolateral and brush border membranes analogous to what has been reported for angiotensin and insulin receptors; their primary concentration, however, is in the basolateral membranes.
Sundaresan
P R
PR
Department of Pharmacology, University of Rochester Medical Center, New York 14642.
Barac-Nieto
M
M
Stambo
G W
GW
Kelvie
S L
SL
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D005947:Glucose / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000201:enzymology / Q000378:metabolism*; D007684:Kidney Tubules / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013816:Thermodynamics; D015016:Yohimbine / Q000378:metabolism
D005971:Glutamates; D011943:Receptors, Adrenergic, beta; D015016:Yohimbine; D000469:Alkaline Phosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose; D011224:Prazosin