IT IS NOW well established that block of transmem-brane ionic channels is frequently time and voltage dependent.' 2 Although the modulated receptor theory has been most extensively studied for sodium and calcium channels in cardiac tissue,3 it may apply to other membrane receptors as well. The present essay is limited to discussion of sodium-channel blockers and how their time-and voltage-depen...

Single-channel properties of dihydropyridine (DHP)-sensitive calcium channels isolated from transverse tubular (T-tube) membrane of skeletal muscle were explored. Single-channel activity was recorded in planar lipid bilayers after fusion of highly purified rabbit T-tube microsomes. Two populations of DHP-sensitive calcium channels were identified. One type of channel (noninactivating) was activ...

The crude extract of Carthamus oxycantha (Co.Cr) was studied in vitro for its possible spasmogenic and spasmolytic activities. Segments of isolated rabbit jejunum 2-3 cm long were mounted in Tyrode’s solution and aerated with 95% oxygen in carbon dioxide. Isotonic responses were measured on Bioscience oscillograph. Isotonic responses were measured on Bioscience oscillograph. Co.Cr caused dose-d...

Voltage-gated Ca2+ channels play essential roles in control of neurosecretion and muscle contraction. The pharmacological significance of Cav channels stem from their identification as the molecular targets of calcium blockers used in the treatment of cardiovascular diseases, such as hypertension, angina, and arrhythmia, and neurologic diseases, such as pain and seizure. It has been proposed th...

During sustained depolarization, voltage-gated Ca2+ channels progressively undergo a transition to a nonconducting, inactivated state, preventing Ca2+ overload of the cell. This transition can be triggered either by the membrane potential (voltage-dependent inactivation) or by the consecutive entry of Ca2+ (Ca2+-dependent inactivation), depending on the type of Ca2+ channel. These two types of ...

The crude extract of Carthamus oxycantha (Co.Cr) was studied in vitro for its possible spasmogenic and spasmolytic activities. Segments of isolated rabbit jejunum 2-3 cm long were mounted in Tyrode’s solution and aerated with 95% oxygen in carbon dioxide. Isotonic responses were measured on Bioscience oscillograph. Isotonic responses were measured on Bioscience oscillograph. Co.Cr caused dose-d...

In wireless communications, the assumption that the transmitter has perfect channel state information (CSI) is often unreasonable, due to feedback delays, estimation errors, and quantization errors. In order to accurately assess system performance, a more careful analysis with imperfect CSI is needed. In this paper, the impact of partial CSI due to feedback delays in a multiuser Orthogonal Freq...

Mutations of the pore-region residue T442 in Shaker channels result in large effects on channel kinetics. We studied mutations at this position in the backgrounds of NH2-terminal-truncated Shaker H4 and a Shaker -NGK2 chimeric channel having high conductance (Lopez, G.A., Y.N. Jan, and L.Y. Jan. 1994. Nature (Lond.). 367: 179-182). While mutations of T442 to C, D, H, V, or Y resulted in undetec...