title: ANF does not increase total body venous compliance in conscious rats with myocardial infarction.
abstract: To test the hypothesis that atrial natriuretic factor (ANF) increases total body venous compliance through venodilation and thereby reduces cardiac preload, we compared the systemic hemodynamic effects of ANF (99-126) with the venodilator nitroglycerin in conscious rats with myocardial infarction (mean infarct size 25%) induced by coronary artery ligation 3 wk previously. A 30-min ANF infusion (0.5 microgram.kg-1.min-1) decreased mean arterial pressure, central venous pressure, and blood volume by 11 mmHg, 0.8 mmHg, and 3 ml/kg, respectively (P less than 0.02). Nitroglycerin (10 micrograms.kg-1.min-1) similarly reduced arterial and venous pressures (7 and 0.6 mmHg; P less than 0.02) but increased blood volume by 2 ml/kg (P less than 0.05). Both ANF and nitroglycerin reduced mean circulatory filling pressure (MCFP) by 1 mmHg (P less than 0.05). Compared with vehicle infusion, nitroglycerin increased total body vascular compliance as derived from serial MCFP measurements taken during 10% blood volume changes (2.09 +/- 0.12 vs. 2.76 +/- 0.32 ml.kg-1.mmHg-1; P less than 0.05) and reduced extrapolated unstressed volume (34.96 +/- 1.10 vs. 23.79 +/- 3.80 ml/kg; P less than 0.02). In contrast, ANF had no effect on either measurement. These data suggest that ANF and nitroglycerin reduced cardiac filling pressure through different mechanisms; the lack of effects of ANF on total body venous compliance and unstressed volume does not support its venodilating effect in these rats postmyocardial infarction.
authors.affiliation: Alton Ochsner Medical Foundation, New Orleans, Louisiana 70121.
authors.forename: Y
authors.initials: Y
authors.lastname: Chien
authors.forename: B L
authors.initials: BL
authors.lastname: Pegram
authors.forename: M B
authors.initials: MB
authors.lastname: Kardon
authors.forename: E D
authors.initials: ED
authors.lastname: Frohlich
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001810:Blood Volume / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology*; D005996:Nitroglycerin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014655:Vascular Resistance / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects; D014680:Veins / Q000187:drug effects*
chemical_list: D009320:Atrial Natriuretic Factor; D005996:Nitroglycerin