Fig. 8. Effects of bolus injections of adrenaline, phenylephrine and isoproterenol (2 and 10 µg kg^-1) on haemodynamic variables in the recovered South American rattlesnakes Crotalus durissus. A–D represent the group with a vascular occluder, and E–G represent the group without a vascular occluder. P_sys, mean systemic blood pressure; P_CV, central venous blood pressure; fH, heart rate; MCFP, mean circulatory filling pressure. Black bars represent control values. Grey bars represent values after injection of the various adrenergic agonists. Values are means ± S.E.M. (N=4) for each group. * indicates a significant difference relative to control values. (1 cm H₂O=0.098 kPa.)