Instantaneous Rate Of Change
Mostrando 13-22 de 22 artigos, teses e dissertações.
-
13. Calcium and potassium currents in muscle fibres of an insect (Carausius morosus).
1. A three electrode voltage-clamp was used to investigate membrane currents in the skeletal muscle fibres of the stick insect, Carausius morosus. Contraction was blocked by hypertonic solutions. 2. Membrane currents elicited by step depolarizations consisted of an inward current, an early outward current and a delayed outward current. 3. The reversal potent
-
14. Pressure-flow studies in man: effect of atrial systole on left ventricular function
In order to evaluate the effects of atrial contraction on left ventricular function, the pressure gradient technique was used to measure instantaneous aortic blood flow and pressure in nine patients, six having complete heart block and three having normal sinus rhythm. From these data both left ventricular stroke volume and stroke work were calculated. Ventr
-
15. Water permeability of ventricular cell membrane in choroid plexus epithelium from Necturus maculosus.
1. The osmotic water permeability Lp and the relations between the flows of H2O, K+ and Cl- were studied in the ventricular membrane of the epithelium from the choroid plexus of Necturus maculosus. 2. The flows were induced by abrupt changes in external osmolarity of the ventricular solution. Solution changes were convective and no effects of unstirred layer
-
16. Electrical restitution in the endocardium of the intact human right ventricle.
OBJECTIVE--To characterise electrical restitution in the intact human heart. PATIENTS AND METHODS--A series of monophasic action potential electrical restitution curves were constructed from a single right ventricular endocardial site in eight patients (three men) without structural heart disease aged 52-68 (mean 55 years). A combination pacing/monophasic ac
-
17. Force responses to rapid length changes in single intact cells from frog heart.
1. Force transients in response to step perturbations in length were recorded in intact atrial cells from frog heart at various temperatures (6-15 degrees C). Length changes of various sizes and in either direction, complete in 0.5 ms, were applied to single myocytes near slack length (initial sarcomere length 2.1-2.2 microns) just before the peak of an isom
-
18. Inward rectification in frog skeletal muscle fibres and its dependence on membrane potential and external potassium.
1. Experiments were carried out using a voltage-clamp technique to investigate the dependence of inward rectification on membrane potential and on the equilibrium potential for K+, changed either by changing [K]o or changing [K]i. 2. The relationship between gK, the potassium chord conductance, and membrane potential depended on membrane potential and [K]o,
-
19. Mechanism of action of GABA on intracellular pH and on surface pH in crayfish muscle fibres.
1. The mode of action of gamma-aminobutyric acid (GABA) on intracellular pH (pHi) and surface pH (pHs) was studied in crayfish muscle fibres using H(+)-selective microelectrodes. The extracellular HCO3- concentration was varied (0-30 mM) at constant pH (7.4). 2. GABA (5 x 10(-6)-10(-3) M) produced a reversible fall in pHi which showed a dependence on the con
-
20. Differential expression of inward and outward potassium currents in the macrophage-like cell line J774.1.
J774.1 cells, a mouse-derived macrophage-like tumour cell line, were voltage clamped using whole-cell patch-clamp techniques. Cells were maintained in suspension cultures and plated at varying times before recording. The average zero-current potential of long-term adherent (greater than 24 h) cells was -77.6 mV. A tenfold increase in [K]o produced a 49 mV sh
-
21. A study of the electrical characteristics of sodium currents in single ventricular cells of the frog.
1. The generation of action potentials elicited from enzymatically dispersed ventricular cells from the frog, Rana catesbeiana, has been shown to be due to the influx of both Na+ and Ca2+. The maximum rate of rise, the amplitude and the duration at 50% repolarization of the action potential were estimated to be 26.4 +/- 5.1 V/s (n = 8), 110 +/- 2.7 mV (n = 8
-
22. Voltage-dependent calcium currents and cytosolic calcium in equine airway myocytes.
1. The relationship between voltage-dependent calcium channel current (I(Ca)) and cytosolic free calcium concentration ([Ca2+]i) was studied in fura-2 AM-loaded equine tracheal myocytes at 35 degrees C and 1.8 mM Ca2+ using the nystatin patch clamp method. The average cytosolic calcium buffering constant was 77 +/- 3 (n = 14), and the endogenous calcium buff