BLUNTED HUMORAL RESPONSES TO MENTAL STRESS AND PHYSICAL EXERCISE IN CARDIAC TRANSPLANT RECIPIENTS

Since recent results have suggested that the relative neuroendocrine r esponse to physical activity is exaggerated following cardiac transpla ntation we studied the haemodynamic-neuroendocrine responses to mental sa ess, and to physical exercise, in heart transplant recipients free of antihypertensive medication. Ten patients were studied 1.7 years ( mean) after transplantation and compared with 10 age-matched controls. Plasma levels of catecholamines, renin activity, aldosterone, atrial natriuetic factor; calcitonin gene-related peptide (CGRP), and endothe lin were measured, together with blood pressure and heart I ale, durin g mental stress and graded submaximal ergometry. Mental stress increas ed blood pressure in both groups (P<0.02), but heart rate in controls only (P<0.05). Noradrenaline did not change. Adrenaline rose in contro ls only (P<0.05). Plasma renin activity increased in both groups (P<0. 02), while aldosterone increased in controls only P<0.02). Atrial natr iuretic factor; and endothelin were higher in patients (P<0.01). Menta l stress, however; did not induce any changes. No significant differen ces were found in relative changes (Delta%), except for plasma renin a ctivity which was greater in controls (P<0.05). During ergometry, only Delta% noradrenaline was greater in patients (P<0.05). Delta% for all other parameters were either of the same order as in controls, or blu nted Thus, apart from noradrenaline, cardiac transplant recipients, no t receiving antihypertensive medication, do not show an exaggeration i n the relative neuroendocrine response to mental or physical stress.