POSSIBLE MODULATE ANTIDIURETIC HORMONE SECRETION IN RELATION TO CIRCULATING BLOOD VOLUME IN TOTAL ARTIFICIAL HEART IMPLANTED CALVES

Abstract

Introduction: It has been reported that the circulating blood volume (CBV) increased significantly in total artificial heart (TAH) recipient. Participation of several hormonal factors including antidiuretic hormone (ADH) in this CBV increase has been supposed, yet its detailed mechanism is still unclear. We investigated possible modulation of ADH secretion in TAH recipient in chronic animal experiments. Method: Three calves were implanted with a pneumatic TAH, and the other four calves were implanted only with monitoring lines as controls. After two weeks of postoperative period, two groups were compared in: 1) transition of CBV, plasma ADH level (CADH), and plasma osmolality (Posm), 2) response of CADH to infusion of hyperosmolar saline solution (1M NaCl at 0.1ml/kg/min for 30 min) and to restriction of water intake (2L/day for 3days). Results: The postoperative CBV in a TAH calf significantly increased (130 ± 19 ml/kg), while in the other two TAH calves did not increase (92 ± 13 ml/kg), compared with in control calves (104 ± 19 ml/kg). The postoperative CADH and Posm were within the normal range in all calves (CADH: 1.5 ± 1.0 vs 0.8 ± 0.2 pg/ml, Posm: 273 ± 8 vs 273 ± 7, in TAHs vs controls, respectively). Sensitivity of ADH secretion to Posm elevation in the CBV-increased TAH calf was remarkably suppressed compared with the other, two TAH calves without CBV increase, and the control calves. (0.06 vs 0.55 vs 0.21 pg/ml/mOsm/kg±H2O at hyperosmolar saline infusion, and 0.11 vs. 0.43 vs. 0.55 pg/ml/mOsm/kg±H2O at water intake restriction, respectively). Conclusion: In TAH implanted calves, CBV increases occasionally and the ADH secretion in response to plasma osmolality elevation was modulated concomitantly, these phenomena do not occur consistently.