Mechanisms of rapid desensitization to arginine vasopressin in vascular smooth muscle cells

Abstract

This study characterized the rapid desensitization induced by arginine vasopressin (AVP) in vascular smooth muscle cells (VSMC) in culture. The Ca2+ mobilization response and, in some experiments, the intracellular pH changes were used as a probe for the desensitization phenomenon. In VSMC, AVP desensitization was homologous, concentration dependent, and occurred in less than 30 s. The desensitization was complete with 10(-7) M AVP. Receptor occupancy was a critical factor in the maintenance of desensitization, since complete hormone washing by acid glycine buffer produced an earlier (less than 5 min) recovery of the cell response, whereas partial hormone washing with saline (pH 7.4) required 15 min to produce any significant recovery. Protein kinase C activation was a significant mechanism in AVP desensitization, because protein kinase C downregulation inhibited the desensitization phenomenon. Receptor internalization was, however, not important for the desensitization phenomenon, since it still occurred at 4 degrees C. Treatment with pertussis toxin did not affect the Ca2+ mobilization response but decreased the AVP-mediated intracellular alkalinization, therefore suggesting that a Gi or Go protein may be involved in some but not all the aspects of the AVP signal transduction and the desensitization phenomena.

Long Lasting Inhibition of Adenylyl Cyclase Selectively Mediated by Inositol 1,4,5-Trisphosphate-evoked Calcium Release

“…2B), or Ro 31-8220 (10 M, not shown) prevent AVP from inhibiting AC. Indeed, and consistent with earlier work suggesting that protein kinase C tonically represses signaling from the AVP receptor (46,47), inhibition of protein kinase C exaggerated the ability of AVP to inhibit AC. After preincubation with 10 M Ro 81-3220 for 5 min, a maximal concentration of AVP inhibited forskolinevoked AC activity by 57 Ϯ 1% (n ϭ 3, versus 35 Ϯ 2% without …”

Mechanisms of desensitization of the adrenocorticotropin response to arginine vasopressin in ovine anterior pituitary cells

“…The lack of involvement of PKC in desensitization of the ACTH response to AVP suggests AVP receptor subtype-specific differences in mechanisms of desensitization of vasopressin receptors: the V1a vasopressin receptor, which is expressed in the liver, brain and vasculature (Birnbaumer 2000), is desensitized via PKCmediated receptor phosphorylation (Caramelo et al 1991, Gallo-Payet et al 1991, Ancellin et al 1997, Ancellin & Morel 1998. Differences in the mechanisms of desensitization might play an important role in the regulation of responsiveness to AVP in different tissues.…”

“…Although these receptors are structurally distinct from V1b receptors (45·5% amino-acid sequence homology in the human (De Keyzer et al 1994)), they share similar signaling properties: they have almost identical affinity for AVP (Jard et al 1986), both are coupled to PLC (Birnbaumer 2000), and both undergo desensitization after exposure to AVP. In the case of the V1a receptor, desensitization appears to be mediated, at least in part, by PKC-mediated phosphorylation of the receptor (Caramelo et al 1991, Gallo-Payet et al 1991, Ancellin et al 1997, Ancellin & Morel 1998. Given the pharmacologic similarities between the two receptor subtypes, the molecular mechanisms involved in their desensitization might be expected to be similar.…”

Glucose-induced downregulation of angiotensin II and arginine vasopressin receptors in cultured rat aortic vascular smooth muscle cells. Role of protein kinase C.

“…45Ca2" efflux studies were performed as previously described (24,40,41 ). Briefly, after exposure to the test media, confluent VSMC on 35-mm dishes were washed with physiological saline solution (PSS) and incubated with 1 ml fresh test medium containing 8 MCi 4SCa2+ (specific activity) for 3 h at 37°C to allow preloading of VSMC with 45Ca2+.…”