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. Author manuscript; available in PMC: 2014 May 20.
Published in final edited form as: Peptides. 2013 Mar 15;43:137–145. doi: 10.1016/j.peptides.2013.03.008

Fig. 2.

Fig. 2

Effect of pretreatment with VIP on VPAC2 receptor desensitization in cells treated with MβCD and in cells transfected with caveolin-1 siRNA. Adenylyl cyclase activity in response to VIP was measured as increase in cAMP formation in control cells, and in cells treated with MβCD or expressing caveolin-1 siRNA before (control) and after treatment of the cells with 1 μM VIP for various times up to 30 min (A) or different concentrations of VIP for 30 min (B). Desensitization of VPAC2 receptors was assessed by the decrease in cAMP response after treatment with VIP. Results are expressed as percent of control response to VIP before pretreatment. Basal levels (2.3 ± 0.3 to 2.8 ± 0.3 pmol/mg protein) and increase in response to VIP (15.2 ± 2.1 to 16.3 ± 2.5 pmol/mg protein) were not significantly different in control cells, and in cells treated with MβCD or transfected with caveolin-1 siRNA. Desensitization of VPAC2 receptors was dependent on the concentration of VIP and time of pretreatment in control cells, and in cells treated with MβCD or transfected with caveolin-1 siRNA. Desensitization of VPAC2 receptors, however, was significantly attenuated in cells treated with MβCD or transfected with caveolin-1 siRNA. Values are expressed as means ± SE of 4 experiments.