Potassium channels represent the dominant ion conductance of vascular smooth muscle cell membranes and play a major role in the regulation of membrane potential (18,19). Membrane potential, in turn, regulates the open state probability of voltage-gated Ca channels (18,19). Thus, as illustrated in Fig. 1, the closure of K channels and the loss of outward K current lead to depolarization, opening...

Kim, Nari, Jin Han, and Euiyong Kim. Effects of prostaglandin F2 on membrane currents in rabbit middle cerebral arterial smooth muscle cells. Am J Physiol Heart Circ Physiol 284: H1018–H1027, 2003; 10.1152/ajpheart. 01022.2001.—Although PGF2 affects contractility of vascular smooth muscles, no studies to date have addressed the electrophysiological mechanism of this effect. The purpose of our i...

Neurons and networks undergo a process of homeostatic plasticity that stabilizes output by integrating activity levels with network and cellular properties to counter longer-term perturbations. Here we describe a rapid compensatory interaction among a pair of potassium currents, I(A) and I(KCa), that stabilizes both intrinsic excitability and network function in the cardiac ganglion of the crab...

Neural circuits are composed of diverse cell types whose firing properties reflect their intrinsic ionic currents. GABAergic and non-GABAergic neurons in the medial vestibular nuclei, identified in GIN and YFP-16 lines of transgenic mice, respectively, exhibit different firing properties in brain slices. The intrinsic ionic currents of these cell types were investigated in acutely dissociated n...

Flow-mediated vasodilation is endothelium dependent. We hypothesized that flow activates a potassium channel on the endothelium, and that activation of this channel leads to the release of the endogenous nitrovasodilator, nitric oxide. To test this hypothesis, rabbit iliac arteries were perfused at varying flow rates, at a constant pressure of 60 mm Hg. Increments in flow induced proportional i...

This study was designed to isolate Ca2+-activated K+ current (I(KCa)) and elucidate its physiological significance in freshly isolated interstitial cells of Cajal (ICCs) of guinea-pig stomach. Single ICC was freshly isolated by enzymatically dissociating from myenteric border of gastric antrum free of circular muscles, and conventional whole-cell voltage clamp technique including immunohistoche...

The natural flavone acacetin inhibits several voltage-gated potassium currents in atrial myocytes, and has anti-atrial fibrillation (AF) effect in experimental AF models. The present study investigates whether acacetin inhibits the Ca2+-activated potassium (KCa) currents, including small conductance (SKCa1, SKCa2, and SKCa3), intermediate conductance (IKCa), and large-conductance (BKCa) channel...

cTnI(P82S) (cTnI(P83S) in rodents) resides at the I-T arm of cardiac troponin I (cTnI) and was initially identified as a disease-causing mutation of hypertrophic cardiomyopathy (HCM). However, later studies suggested this may not be true. We recently reported that introduction of an HCM-associated mutation in either inhibitory-peptide (cTnI(R146G)) or cardiac-specific N-terminus (cTnI(R21C)) of...

This study aimed to investigate the vasoactivity of sulfur dioxide (SO2), a novel gas identified from vascular tissue, in rat thoracic aorta. The thoracic aorta was isolated, cut into rings, and mounted in organ-bath chambers. After equilibrium, the rings were gradually stretched to a resting tension. Isometric tension was recorded under the treatments with vasoconstrictors, SO2 derivatives, an...