51 research outputs found
Effects of Isolation Period Difference and Beam-Column Stiffness Ratio on the Dynamic Response of Reinforced Concrete Buildings
The morphological adaptation of Lithocodium aggregatum Elliott (calcareous green alga) to cryptic microhabitats (Lower Aptian, Spain): an example of phenotypic plasticity
Influence of thyroid status on postnatal maturation of calcium channels, beta-adrenoceptors and cation transport ATPases in rat ventricular tissue.
In order to examine the influence of thyroid hormones on the postnatal development of cardiac excitation-contraction coupling, newborn rats were made hypo- or hyperthyroid, and several key factors involved, directly or indirectly, in Ca2+ signaling: L-type Ca2+ channels (1,4-dihydropyridine receptors), Ca(2+)-release channels of sarcoplasmic reticulum (ryanodine receptors), beta-adrenoceptors, thapsigargin-sensitive Ca(2+)-ATPase and Na(+)-K(+)-ATPase (enzyme activity and ouabain receptors), were investigated in membrane fractions from ventricular tissue, collected on day 21. Hypothyroidism induced a moderately lower myocardial density of 1,4-dihydropyridine and ryanodinerece receptors (reduced by 23% and 31%, respectively, with respect to euthyroid controls), and much reduced levels of beta-adrenoceptors, Ca(2+)-ATPase and Na(+)-K(+)-ATPase activities. Hyperthyroidism induced only a moderate (22%) decrease in the myocardial density of 1,4-dihydropyridine receptors and a marked (240%) increase of the alpha 2 isoform of Na(+)-K(+)-ATPase. To analyse the subsarcolemmal localization of L-type channels, microsomal fractions were subfractionated by density equilibration in sucrose gradient. In gradients from control and hyperthyroid rats, most 1,4-dihydropyridine receptors were recovered in high-density subfractions, their distribution following that of ryanodine receptors, whereas, in gradients from hypothyroid rats, most 1,4-dihydropyridine receptors were recovered in low-density subfractions, together with beta-adrenoceptors and Na(+)-K(+)-ATPase. We conclude that thyroid hormones are important for the postnatal changes in the myocardial density of several channels and pumps involved in Ca2+ fluxes, as well as for the postnatal redistribution of L-type Ca2+ channels from non-junctional sarcolemma to junctional structures, a key process for the efficient operation of excitation-contraction coupling in adult ventricular tissue
New Computational Formulas for Special Numbers and Polynomials Derived from Applying Trigonometric Functions to Generating Functions
Dual Detection for Capillary Isoelectric Focusing with Refractive Index Gradient and Absorption Imaging Detectors
Soft-Story Effects on the Behavior of Fixed-Base and LRB Base-Isolated Reinforced Concrete Buildings
Analysis of α-keratins in the horns of rhinoceros and buffalo by non-native capillary isoelectric focusing
- …