Sites of action of arginine vasotocin in the nephron of the bullfrog kidney.
The nature and location of arginine vasotocin (AVT) V2-type receptors in the bullfrog kidney with respect to cellular 3',5'-cyclic monophosphate (cAMP) production in response to AVT were studied in microdissected segments of the nephron and urinary bladder. The basal levels of cAMP were similar in renal corpuscles, proximal, distal convoluted, and connecting tubules, and urinary bladder of normal bullfrogs. A marked dose-dependent increase in cAMP production by AVT occurred in preparations from both the connecting tubule and the urinary bladder. The minimum effective and half-maximal concentrations of AVT on the connecting tubule were about 100 nM and 2 microM, respectively. No activation by AVT was observed in renal corpuscles and proximal tubules. These results suggest that V2-type AVT receptors exist in the connecting tubule of the nephron and the urinary bladder. The lack of hormonal activation of cAMP production observed in some tissues may reflect either the total absence or the presence of minor amounts of hormonal receptors associated with the cAMP-generating system in bullfrog nephron segments.
Uchiyama
M
M
Department of Oral Physiology, School of Dentistry at Niigata, Nippon Dental University, Japan.
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000242:Cyclic AMP / Q000096:biosynthesis; D066298:In Vitro Techniques; D007668:Kidney / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D009399:Nephrons / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D011892:Rana catesbeiana; D017483:Receptors, Vasopressin / Q000187:drug effects / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D014668:Vasotocin / Q000494:pharmacology*
D017483:Receptors, Vasopressin; C034862:vasotocin receptor; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D014668:Vasotocin