This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by BARNES, L. D. Articles by DOUSA, T. P. Search for Related Content PubMed PubMed Citation Articles by BARNES, L. D. Articles by DOUSA, T. P.

Subcellular Distribution of the Enzymes Related to the Cellular Action of Vasopressin in Renal Medulla

Nephrology Research Laboratories, Department of Medicine (Division ofNephrology and Internal Medicine) and Department of Physiology and Biophysics, Mayo Clinic and Foundation Rochester, Minnesota 55901

Abstract

Subcellular distribution of the enzymes related to the cellular action of antidiuretic hormone was studied in bovine renal medulla.

The highest activity of vasopressin-stimulated adenylate cyclase was found in plasma membranes. The basal activity increased two times above homogenate while vasopressin-stimulated and NaF-stimulated activities both increased five times. Adenylate cyclase activity was present also in other particulate fractions, but it was not significantly stimulated by vasopressin.

Cyclic AMP phosphodiesterase was predominantly located in the cytosol when assayed with 0.5 mM cyclic AMP or with 5 µM cyclic AMP. However, with the latter concentration of cyclic AMP more activity remained associated with the particulate fractions and was more inhibited by theophylline. The highest cyclic AMP-stimulated protein kinase activity occurred in the cytosol. Protein kinase activity present in other subcellular fractions was not markedly stimulated by cyclic AMP. Protein phosphatase activity was highest in cytosol when assayed using ³²P-histones, ³²P-plasma membrane proteins, and ³²P-cytosolic proteins. The activity was unaffected by 10^–6M to 10^–4M cyclic AMP or cyclic GMP. Theactivity was completely inhibited by 10 mM ZnSO₄ and 10 mM CuSO₄; 10 mM NaF inhibited the activity by approximately 14%.

The enzymes related to the cellular action of vasopressin are predominantly localized in thecytosol, except for the vasopressin-sensitive adenylate cyclase which is plasma membrane bound.To mediate the effect of antidiuretic hormone and act on the luminal plasma membrane these soluble enzymes and their substrates should be compartmentalized, possibly by a system of cytoplasmic microtubules. (Endocrinology 96: 119, 1974)

Received May 6, 1974.