Atrial natriuretic factor in spinal cord injury

Atrial natriuretic factor (ANF) concentrations were determined in matched cervical (n = 6) and thoracic (n = 7) spinal cord injured subjects in comparison to control volunteers (n = 6). In the spinal cord injury groups sampling conditions were controlled for posture, time of day, smoking status, and dietary intake. There were no between groups differences relative to age, plasma renin activity, plasma aldosterone, plasma antidiuretic hormone, plasma osmolality, urine sodium or potassium excretion, or creatinine clearance. In comparison to ambulatory normals at comparable levels of sodium intake (14.4 +/- 4.8 ng/dL) both spinal cord injury groups exhibited elevated recumbent plasma aldosterone values 26.8 +/- 2.54 ng/dL (thoracic) and 20.9 +/- 4.38 ng/dL (cervical). Plasma ANF concentrations in thoracic cord injured subjects were 39.22 +/- 4.00 pg/mL and 119.5 +/- 33.40 pg/mL in cervical cord injured individuals, contrasting with normal control population values of 13.35 +/- 1.29 pg/mL. These data suggest that in the spinal cord injury state, there is either a failure of end organ response to ANF, or the ascendancy of counteracting hormonal and hemodynamic mechanisms over the effects of ANF.