Cardiovascular function in adrenalectomized pekin ducks (Anas platyrhynchos)

1. 1. Cardiovascular function was progressively impaired in Pekin ducks following surgical adrenalectomy. 2. 2. Diastolic and systolic arterial pressures (P_a) were respectively 45% and 28% lower in adrenalectomized (ADX) ducks than in sham-operated (SHAM) controls within 3 days after surgery. 3. 3. Adrenalectomy caused cardiac frequency (φ_H) to approximately double, diminished cardiac stroke volume, decreased body weight, and decreased plasma norepinephrine, epinephrine, osmolal, Na and Cl concentrations. 4. 4. Adrenalectomy did not alter blood volume, hematocrit, or plasma concentrations of Ca and Mg. 5. 5. Administration of a synthetic glucocorticoid, betamethasone, prevented hypotension and prolonged the survival of ADX ducks. 6. 6. ADX and SHAM ducks maintained with betamethasone for up to 8 days did not differ in P_a, body weight, hematocrit, or plasma concentrations of Na and K. 7. 7. These experiments demonstrate the critical importance of glucocorticoid activity for blood pressure, Na and Cl regulation in birds.