Figure 3. βARK1 peptide expression prevents voltage-dependent inhibition of I_Ca.

A, bar graph summarizing the effects of βARK1 peptide expression on I_Ca inhibition induced by noradrenaline (10 μm, filled bars), somatostatin (500 nm, shaded bars) and angiotensin II (500 nm, open bars). Uninj, uninjected control cells. Bars represent means ±s.e.m. for the number of cells indicated. Somatostatin and angiotensin II inhibition was recorded in cells preinjected with 200 μg ml⁻¹βARK1 construct. Cells were recorded 48 h after injection. *** P < 0.0001, compared with the respective controls. Inset, I_Ca amplitude was measured isochronally 4 ms after the onset of the test pulse (dashed line) from the zero current level obtained in the presence of cadmium (Cd²⁺, 500 μm). I_Ca was elicited from −70 to +5 mV. B, bar graph summarizing the effects of the βARK1 peptide on the facilitation ratio (postpulse : prepulse) in the absence or presence of neurotransmitters as indicated. □, control; ▪, βARK1 peptide. *** P < 0.0001.