Fig. 4.

Inhibition of l-AVP mediated receptor activation by NOX-F37 (▴) and its 40-kDa PEGylated variant (■). (A) V₂ receptor was stimulated with 1 nM l-AVP in the presence of the indicated concentrations of Spiegelmer, the resulting cAMP formation was measured, and the IC₅₀ (1 nM) was determined at the Spiegelmer concentration of half-maximal cAMP formation. (B) V_1a receptor was stimulated with 5 nM l-AVP in the presence of the indicated concentrations of Spiegelmer, the resulting Ca²⁺ release was measured, and the IC₅₀ (6.1 nM) was determined at the Spiegelmer concentration of half-maximal Ca²⁺ release.