Large-conductance calcium-sensitive BK channels are one of the potassium channels that
hyperpolarize the neurons and are encoded by KCNMA1 (6,7).
Oxt is thought to
hyperpolarize the pain signalcarrying nerves.
This influx of calcium appears necessary to stimulate the development of the mature form of the chloride ion transporter KCC2 (neuronal potassium-chloride symporter) that allows the neurons to
hyperpolarize to their adult resting potential.
Most agents that activate release of NO from the endothelium also
hyperpolarize both endothelial and smooth muscle cells (35).
Physiologically, activation of [BK.sub.Ca] channels would
hyperpolarize MASMCs, thereby closing VDCCs, reducing intracellular [Ca.sup.2+] and relaxing SMCs (Nelson and Quayle 1995).
When activated, these receptors
hyperpolarize the membrane potential and/or fix the membrane potential at voltages below the action potential threshold.
The PIA sends projections to NGC (74), NMC (71,75) and NPM (76) of the medullary region, which in turn project to the spinal cord (72,75,77) to
hyperpolarize motoneurons to control the spinal circuits for inducing atonia during REM sleep (78,79).
Another vasodilator action of the endothelium is mediated by the release of substances-including nitric oxide, prostacyclin, and eicosatrienoic acid-that
hyperpolarize smooth muscle by activating calcium-dependent potassium channels and are collectively referred to as endothelium-derived hyperpolarizing factors (22).
The membrane will become depolarized next to the initial site of depolarization, and the potential will increase (i.e.,
hyperpolarize) with distance away from the initial site of depolarization until the membrane potential is equal to the resting potential.
The two retinas differ morphologically and physiologically: the ciliary photoreceptors of the distal retina
hyperpolarize in response to light, whereas the rhabdomeric photoreceptors of the proximal retina depolarize in response to light (Hartline, 1938; Wald and Seldin, 1968; McReynolds and Gorman, 1970; Gomez and Nasi, 1994).