FIGURE 3.

Gq coupling is required for full ERK activation by an α1A agonist in AMVMs. AMVMs cultured 24 h in serum-free medium were treated 5 min with the drugs indicated, and phospho-ERK and total-ERK were quantified by immunoblot. A6=A61603; GqKI=α1A with Gq knockin. PMA=phorbol myristate acetate was a positive control for ERK activation in the GqKI. Praz=prazosin, an α1-AR antagonist, blocks A61603 activation of ERK in both WT and GqKI, confirming an α1 effect. Sigmoidal dose-response curves were fit in Prism; p values are from unpaired t test of the calculated Emax of A6 WT and A6 GqKI; N = cultures from different hearts.