Figure 1

Experimental protocols. Overview of the study, indicating one week gentling and post-surgical recovery periods, and twice-weekly experimental sessions for randomised protocols (a). Protocols for the acute administration of incrementing doses of the α-adrenergic agonist phenylephrine at five minute intervals (b), and the β-adrenergic agonist dobutamine at ten minute intervals (c). Sodium nitroprusside (SNP) was injected at the initiation of each experiment to confirm vascular access port (VAP) patency. Sal represents saline injection to flush the VAP. All solutions were administered as a bolus.