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R J Storella

Publications and source records attributed to R J Storella.

25 records · Page 2Linked to original sources
PubMed1986

Frequency-dependence of neuromuscular blockade in the presence of d-tubocurarine.

The frequency-dependence of neuromuscular blockade in the presence of d-tubocurarine (dTC) was studied in the vascular perfused rat phrenic nerve-hemidiaphragm preparation by intracellular recording. Endplate potential (EPP) amplitude decreased as the frequency of stimulation increased (2.5-40 Hz). Additionally, the slopes of the regression lines of EPP amplitude versus the log of stimulation frequency decreased when the dTC concentration was increased. Since the dependence of neuromuscular blockade on frequency was not enhanced by higher concentrations of dTC, the postjunctional channel-blocking hypothesis does not sufficiently explain frequency-dependent neuromuscular blockade in the presence of dTC. However, the present results are compatible with the hypothesis that dTC influences neuromuscular blockade via a prejunctional action, affecting acetylcholine release.

Animals↗
PubMed1986

A comparison of chemiluminescent and radioenzymatic methods for the measurement of acetylcholine released from a rat phrenic nerve-hemidiaphragm preparation.

A chemiluminescent assay coupled to a periodide extraction method is described for the measurement of acetylcholine release from the vascular perfused rat phrenic nerve-hemidiaphragm preparation. A direct comparison of the chemiluminescent assay with an established radioenzymatic assay for acetylcholine demonstrates that the two assays are quantitatively equivalent and yield similar limits of sensitivity of approximately 2 pmol, and that the periodide extraction/chemiluminescent assay method is more consistent than the tetraphenylboron extraction/radioenzymatic assay method. Additionally, cholinergic drug interference with the chemiluminescent assay is minimal. The absence of radioactivity and the reduced cost of the chemiluminescent assay make it an attractive alternative to the radioenzymatic assay.

Acetylcholine↗
PubMed1985

d-Tubocurarine sensitivities of a fast and a slow neuromuscular system of the rat.

Fast and slow neuromuscular systems in the rat were compared with respect to their sensitivity to d-tubocurarine (dTC). The fast tibialis anterior was more sensitive than the slow soleus to dTC-induced block of contractile tension when stimulated at either 0.2 or 1.0 Hz. These results in the rat contrast those made by others in the cat. Thus, relative drug sensitivities are not simply related to neuromuscular type.

Animals↗
PubMedDate not supplied

Approximate entropy and point correlation dimension of heart rate variability in healthy subjects.

The contribution of nonlinear dynamics to heart rate variability in healthy humans was examined using surrogate data analysis. Several measures of heart rate variability were used and compared. Heart rates were recorded for three hours and original data sets of 8192 R-R intervals created. For each original data set (n = 34), three surrogate data sets were made by shuffling the order of the R-R intervals while retaining their linear correlations. The difference in heart rate variability between the original and surrogate data sets reflects the amount of nonlinear structure in the original data set. Heart rate variability was analyzed by two different nonlinear methods, point correlation dimension and approximate entropy. Nonlinearity, though under 10 percent, could be detected with both types of heart rate variability measures. More importantly, not only were the correlations between these measures and the standard deviation of the R-R intervals weak, the correlation among the nonlinear measures themselves was also weak (generally less than 0.6). This suggests that in addition to standard linear measures of heart rate variability, the use of multiple nonlinear measures of heart rate variability might be useful in monitoring heart rate dynamics.

Adult↗