Fig. 2.

Effect of dopamine dose on the hypoxic ventilatory response (HVR), reported relative to responses during saline infusion (saline = 100%). High HVR (n = 13), low HVR (n = 17). Intravenous dopamine infusion resulted in a significant reduction in the HVR at each dopamine dose in subjects with high baseline chemosensitivity (black bars, P < 0.01). In contrast, those subjects exhibiting low baseline chemosensitivity showed no main effect of dopamine on the HVR (white bars, P = 0.20). Data are presented as means ± SE. DA, dopamine; number = dose in μg·kg⁻¹·min⁻¹. *P < 0.05 vs. saline.