Fig. 6.

Effect of heterologous overexpression of mutant Gβ4 and Gα_tr on basal facilitation and NE-mediated Ca²⁺ current inhibition. Superimposed Ca²⁺ current traces evoked with the double-pulse voltage protocol (shown in Fig. 4E) in the absence (bottom traces) and presence (top traces) of 10 μm NE for wild-type β4γ4 and Gα_tr- (A), β4(80)γ4- (B), β4(55,88,89)γ4 (C), and β4(55,88,89)γ4 and Gα_tr-expressing (D) neurons.E, Summary graphs of mean ± SEM basal facilitation and Ca²⁺ current inhibition for neurons expressing wild-type and mutant Gβ4γ4 alone or combined with Gα_tr. Final concentration of cDNA injected was 10 ng/μl per subunit. Basal facilitation and Ca²⁺ current inhibition were calculated as described in Figure1E. **p < 0.01 versus control. Numbers in parentheses indicate the number of experiments.