In the rabbit, the sinus node is surrounded by a group of cells which we have termed perinodal fibers. Since sinus node impulses preferentially proceed to the crista terminalis and then spread to the rest of the atrium, we selected the zone of perinodal fibers lying between the sinus node and the crista terminalis for study. Values of transmembrane potentials and the maximum rate of rise (Vmax)...

To explore the molecular mechanisms responsible for the variation in smooth muscle contractile kinetics, the influence of MgATP, MgADP, and inorganic phosphate (P(i)) on force and shortening velocity in thiophosphorylated "fast" (taenia coli: maximal shortening velocity Vmax = 0.11 ML/s) and "slow" (aorta: Vmax = 0.015 ML/s) smooth muscle from the guinea pig were compared. P(i) inhibited active...

We have previously described elevated Lii -Nao countertransport (CT) and Na-K cotransport (CO) in red cells of Caucasian patients from Boston. In this study, we report both transport systems in black patients from Philadelphia. The maximal rate (Vmax) of CT was assayed by measuring the Nao-stimulated Li efflux from cells containing +/- 6 mmol Li/liter. The Vmax of outward cotransport was assaye...

The maximal, no-load, velocity for the contractile element (Vmax) was estimated in 45 patients. The patients included: 17 with normal left ventricular dynamics; eight with volume overload, compensated; 11 with volume overload, decompensated; three with pressure overload; and six with cardiomyopathy. Contractile element velocity (VcE) during isovolumic contraction was estimated in two ways: (1) ...

Tomographic images generated by wave propagation are important in tree inspections and can be performed an economically more accessible way using conventional equipment postprocessed images, but improvements necessary to increase image quality, giving greater reliability the results. The objective of this paper was present a methodological proposal for definition parameters related quality prod...

BACKGROUND AND OBJECTIVES The factors related to the progression of mild aortic stenosis (AS) remain unknown. We wanted to evaluate the long-term outcomes and predictors of echocardiographic progression in patients with mild AS. SUBJECTS AND METHODS We prospectively included 103 consecutive asymptomatic patients (62.1±11.9 years, 31 males) with mild AS. Mild AS was defined as aortic valve (AV...

To understand better how scup can swim twice as fast as carp with its red muscle, we measured the mechanical properties of red muscle bundles in scup. The values of the mean maximum velocity of shortening (Vmax) at 10 degrees C (3.32 muscle lengths s-1) and at 20 degrees C (5.55 muscle lengths s-1; Q10 = 1.69) were nearly the same as those in carp. Isometric force, however, was approximately 50...

We used standard microelectrode techniques to evaluate the effects of lidocaine and quinidine on canine Purkinje fibers at normal pH (7.3) and in the presence of acidosis (pH 6.9). Acidosis alone reduced resting potential, action potential amplitude, and Vmax, while increasing APD90 and conduction time. Lidocaine concentrations of 6 x 10(-6) to 1.5 x 10(-5) M had minimal effect on resting poten...

The study determined the population estimates for Km and Vmax of phenytoin in Thai patients. The serum phenytoin concentrations collected prospectively from outpatients who received phenytoin were analyzed to estimate population pharmacokinetic parameters. There were 197 steady-state concentrations and associated dosage rates (mg/day) from 167 outpatients. The data were analyzed using NONMEM, a...

Unfavorable incidents during cardiac operations due to inadequate cerebral perfusion can be avoided by the utilization of noninvasive blood flow monitoring methods. The purpose of this study was to evaluate monitoring systems for cebrovascular perfusion. We compared currently available blood flow monitoring devices including transcranial Doppler (TCD), central retinal artery color Doppler (CRAD...