Three types of calcium channels have been identified voltage-sensitive, receptor operated (cardiac muscle and vascular smooth muscle) and stretch operated (in some blood vessels) channels. Using electrophysiological and pharmacological techniques, three different types of voltage-gated calcium channels have been identified, namely, L-type (for long lasting, large channels), T–type (for transien...

3-iodothyronamine (T(1)AM) is a novel endogenous relative of thyroid hormone, able to interact with trace amine-associated receptors, a class of plasma membrane G protein-coupled receptors, and to produce a negative inotropic and chronotropic effect. In the isolated rat heart 20-25 microM T(1)AM decreased cardiac contractility, but oxygen consumption and glucose uptake were either unchanged or ...

Artim, Debra E. and Stephen D. Meriney. G-protein-modulated Ca current with slowed activation does not alter the kinetics of action potential-evoked Ca current. J Neurophysiol 84: 2417–2425, 2000. We have studied voltage-dependent inhibition of N-type calcium currents to investigate the effects of G-protein modulationinduced alterations in channel gating on action potential-evoked calcium curre...

Contents 1. Introduction 2. Soil acidity and its indices 2.1. Actual acidity. 2.2. Potential acidity. 2.3. Cation (positive ion) exchange capacity and saturation with bases. 3. Natural reasons for increasing soil acidification 3.1. Leaching regime. 3.2. Soil-forming rocks and plants. 3.3. The distribution of acid soils. 4. The reasons for anthropogenic acidification of soils. The phenomenon of ...

Pyramidal cells of layer V in rat prefrontal cortex display a prominent fast afterdepolarization (fADP) following an action potential. This ADP is blocked by replacing extracellular calcium with magnesium, by the application of the calcium-channel blocker cadmium, and by buffering intracellular calcium at near physiological levels. Thus this fast ADP appears mediated by a calcium-activated curr...

Neurons from bullfrog sympathetic ganglia were voltage-clamped using a single microelectrode in Ringer solution with tetrodotoxin. The M-current (Adams et al. 1982 a) was markedly reduced during the rhythmic outward potassium current induced by caffeine (1-5 mM). This indicates that an elevation of the intracellular concentration of calcium ions by caffeine not only activates the calcium-activa...

In both skeletal and cardiac muscle, the dihydropyridine (DHP) receptor is a critical element in excitation-contraction (e-c) coupling. However, the mechanism for calcium release is completely different in these muscles. In cardiac muscle the DHP receptor functions as a rapidly-activated calcium channel and the influx of calcium through this channel induces calcium release from the sarcoplasmic...