We compared the responses of the pulmonary and mesenteric circulations to Dop and Epi during hypoxia. METHODS. 3 groups (5 controls) of 1-3 d old fentanyl anesthetized piglets (mean weight 1.71 kg) were instrumented to measure cardiac index (Q), hepatic arterial flow (HAf) Mesenteric flow (Mf) systemic (SAP), and pulmonary arterial pressure (PAP). Vascular resistances(SVR, PVR, MVR) were calculated. Severe alveolar hypoxia was induced for 1 h, sats 55 to 60%. Either Dop (n=6) at doses of 2, 10, 32μg/kg/min or Epi(n=6) at 0.2, 1.0, 3.2μg/kg/min were infused in random order.RESULTS. Dop increased PAP but not SAP, worsening SAP/PAP and did not increase Q, Epi increased Q and affected SAP and PAP equally, and did not affect SAP/PAP. High dose Dop increased Mf and Total hepatic flow (THf), and decreased MVR, low dose Epi increased HAf. ANOVA, *=p<0.05, cf hypoxia alone. †=p<0.05 cf Epinephrine, ‡=p<0.05 cf Dop.Table

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During hypoxia with pulmonary hypertension Epi does not affect PAP whereas Dop increases PAP. In contrast to previous observations during normoxia high dose Dop increases gut perfusion. The mechanisms for this difference, possibly due to altered adrenoceptor regulation and function during hypoxia, need further investigation.