Response of atrial natriuretic factor to acute extracellular fluid volume in patients with pheochromocytoma.
BACKGROUND
Patients with pheochromocytoma have been reported to show high plasmatic atrial natriuretic factor (ANF) levels. Its source may not be the atrium because blood volume, the most important physiological stimulus for ANF release, is usually reduced in these patients.


METHODS
To evaluate ANF secretion functional integrity, we studied three patients with pheochromocytoma before and after surgical removal of the tumor. Extracellular fluid (ECF) volume, plasmatic ANF levels, and plasmatic renin activity (PRA) were measured. ANF was measured before and after an acute saline load of 1.5L in 90 min.


RESULTS
Before surgery, ECF volume was normal or reduced, and PRA was normal but decreased after the saline load. By contrast, ANF was elevated and did not change after the saline load. After surgery ANF decreased, ECF volume rose, and the saline load induced a significant increase of plasma ANF and reduction of PRA. ANF was present in significant amounts in tumoral tissue homogenates.


CONCLUSIONS
These data suggest that the tumor was the source of ANF in these patients with pheochromocytoma because high levels of ANF, despite reduced or normal ECF volume, as well as unresponsiveness to acute saline infusion, were found before surgery with subsequent normalization after tumor removal.
Paniagua
R
R
Unidad de Investigación Medica en Enfermedades Nefrólogicas, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, IMSS, Cuauhtémoc 330, Col. Doctores, 06725 Mexico City, Mexico. jrpaniagua@terra.com.mx
Rodríguez
E
E
Amato
D
D
Sánchez
G
G
Ron
O
O
Rodríguez
F
F
Herrera-Acosta
J
J
D000310:Adrenal Gland Neoplasms / Q000097:blood* / Q000737:chemistry / Q000601:surgery; D000328:Adult; D009320:Atrial Natriuretic Factor / Q000097:blood* / Q000737:chemistry / Q000378:metabolism; D001810:Blood Volume; D005110:Extracellular Space / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D009318:Natriuresis; D010673:Pheochromocytoma / Q000097:blood* / Q000737:chemistry / Q000601:surgery; D011184:Postoperative Period; D012083:Renin / Q000097:blood; D012636:Secretory Rate / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology*
D012965:Sodium Chloride; D009320:Atrial Natriuretic Factor; D012083:Renin