Effect of cardiac filling pressures on the release of atrial natriuretic peptide during exercise in heart transplant recipients.
OBJECTIVE
To determine the influence of body posture and central hemodynamics on the plasma levels of immunoreactive atrial natriuretic peptide (irANP) during exercise in cardiac transplant patients.


METHODS
Central hemodynamics, mixed expired gas and ventilatory measurements, and venous blood sampling (for irANP determination) were obtained in cardiac transplant patients at rest and during supine (n = 12) or upright (n = 12) graded cycle exercise. Cardiopulmonary and irANP responses to exercise were compared between the upright and supine postures.


RESULTS
At rest (supine), irANP concentrations were similar in both groups (172 +/- 87 pg/mL supine and 182 +/- 72 pg/mL upright) and did not correlate with resting supine central hemodynamics. During exercise, central filling pressures increased in both groups but patients exercising in the supine position had a greater increase. Peak exercise right atrial pressure was 12 +/- 4 mmHg supine versus 7 +/- 5 mmHg upright (P < 0.005). Peak exercise pulmonary capillary wedge pressure was 22 +/- 6 mmHg supine versus 14 +/- 5 mmHg upright (P < 0.005). At peak exercise, irANP levels were greater in the supine than upright position (419 +/- 166 pg/mL supine versus 277 +/- 40 pg/mL upright, P < 0.05). The change in irANP from rest to peak exercise correlated (P < 0.05) with changes in pulmonary capillary wedge pressure (r = 0.67), systolic pulmonary artery pressure (r = 0.78) and right atrial pressure (r = 0.53). There was, however, no correlation between change in irANP and peak oxygen consumption, change in heart rate or change in mean arterial blood pressure.


CONCLUSIONS
In cardiac transplant recipients, exercise is a stimulus for ANP secretion, and augmentation in plasma irANP levels during exercise is modulated by changes in central hemodynamics.
Bussières-Chafe
L M
LM
Faculty of Kinesiology, University Hospital, University of Western, Ontario, London.
Pflugfelder
P W
PW
Henderson
A R
AR
MacKinnon
D
D
Taylor
A W
AW
Kostuk
W J
WJ
D000328:Adult; D009320:Atrial Natriuretic Factor / Q000502:physiology*; D001784:Blood Gas Analysis; D001944:Breath Tests; D015444:Exercise / Q000502:physiology*; D016027:Heart Transplantation / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011187:Posture / Q000502:physiology*; D012146:Rest; D016683:Supine Position; D013599:Systole
D009320:Atrial Natriuretic Factor