The present studies were conducted in conscious, instrumented @entity35 to evaluate measurements of aortic peak flow velocity ( @entity18179 ) as an index of myocardial contractility. Because our previous studies had characterized/verified procedures to determine pressure-derived indices of contractile function in the anesthetized, ventilated, open-chest @entity35 , we first correlated @entity18179 with (a) maximum rate of left ventricular pressure development (max +dP/dt) and (b) a contractility index derived by dividing max +dP/dt by left ventricular pressure at max +dP/dt [(dP/dt)/P] in anesthetized @entity35 (n = 5). The positive inotropic agent, @entity3044 , given by bolus intravenous injection (0.2 microgram), significantly and concurrently increased dP/dt, (dP/dt)/P, and @entity18179 . The negative inotropic agent, @entity1169 , given by bolus intravenous injection (2 mg/kg), significantly and concurrently attenuated all of the above measurements. When control, @entity3044 , and @entity1169 responses were used to calculate multivariate correlation coefficients among dP/dt, (dP/dt)/P, and @entity18179 , r values ranged from 0.74 ( @entity18179 vs. dP/dt) to 0.84 (dP/dt vs. (dP/dt)/P) to 0.91 ( @entity18179 vs. (dP/dt)/P). A separate group of @entity35 (n = 4) was surgically implanted with ascending aortic blood flow sensors, carotid artery and jugular vein catheters. Intravenous @entity3044 (0.2 microgram, bolus) elicited increased cardiac (heart rate and cardiac output) and decreased peripheral vascular resistance (mean arterial blood pressure) beta-adrenergic receptor agonist effects. @entity1169 (2 mg/kg, i.v. bolus) produced hemodynamic effects consistent with cardiovascular beta-adrenergic receptor blockade. @entity3044 and @entity1169 had directionally appropriate, and significant effects on @entity18179 in the conscious @entity35 . When compared with @entity18179 values under control conditions in the anesthetized @entity35 , conscious @entity35 values are approximately double those observed under anesthesia; however, the relative @entity18179 responses to @entity3044 and @entity1169 were not affected. Therefore, the present studies provide evidence that aortic @entity18179 can be utilized as an estimate of heart contractile performance, i.e., myocardial contractility, in the conscious, instrumented @entity35 .

Aortic peak flow velocity as an index of myocardial contractility in the conscious XXXX .

@entity35 :: ('10116', 'Species') :: ['rat', 'rats'] @entity3044 :: ('MESH:D007545', 'Chemical') :: ['Isoproterenol', 'isoproterenol'] @entity18179 :: ('CHEBI:55309', 'Chemical') :: ['PFV'] @entity1169 :: ('MESH:D011433', 'Chemical') :: ['propranolol', 'Propranolol']
@entity35 :: (10116,Species) :: ['rat']
