Adrenergic regulation of calcium‐activated potassium current in cultured rabbit pigmented ciliary epithelial cells

Abstract

1. The effects of adrenergic agonists on K¤ currents were studied in cultured rabbit pigmented ciliary epithelial (PCE) cells.

Adrenaline-induced hyperpolarization of mouse pancreatic islet cells is mediated by G protein-gated inwardly rectifying potassium (GIRK) channels

“…The absence of such a component in the total I Tpn-Q suggests that adrenaline and Tpn-Q inhibit the same current, which was not detected by the total I Tpn-Q measurement since it had been already inhibited by adrenaline. While BK channels are stimulated by α1-and β-adrenergic pathway activation in other tissues [7,32,47], they are inhibited by somatostatin in the HIT insulinoma cells [44]. Since the α 2 -adrenoceptor-mediated inhibitory action of adrenaline predominates in β-cells, it appears reasonable that adrenaline leads to BK inhibition in these cells.…”

Distribution of alpha‐1 adrenoceptor subtypes in RNA and protein in rabbit eyes

“…(1980) demonstrated that prazosin lowered IOP in the rabbit eye by decreasing the rate of aqueous humor production. Ryan et al . (1998) suggested that potassium channels coupled to alpha‐1 ARs might modulate fluid secretion by the ciliary epithelium.…”

“…In vivo studies have revealed that alpha‐1 ARs are involved in the regulation of intraocular pressure (IOP) in rabbits and monkeys (Kiuchi et al ., 1992; Nishimura et al ., 1993; Wang et al ., 1997; Zhan et al ., 1998; Okada & Gregory, 2001). Moreover, alpha‐1 ARs have been found to regulate cellular functions in cultured endothelial cells from various ocular regions in several species (Walkenbach et al ., 1992; Moroi‐Fetters et al ., 1995; Ryan et al ., 1998). However, which subtype(s) of alpha‐1 AR is involved in the ocular functions remains to be clarified.…”

K+ channel currents in rat ventral prostate epithelial cells

“…The activation of K þ channels and membrane hyperpolarization by the Ca 2þ -or cAMP-mediated secretagogue is reported in many cases of exocrine cells [7,23,24]. The role of the BK type of K(Ca) channel in luminal K þ secretion or in electrogenic Cl À secretion has been suggested in various exocrine cells, including the pigmented ciliary epithelium of rabbit [25], the pancreatic acinar cells of pig [26], human vas deferens epithelial cells [27], and the acinus of the mouse salivary gland [28]. The IK type of K(Ca) channel also plays an important role in the electrolyte-fluid secretion of the pancreatic acini of some species [24] and of the colonic crypt [23,29].…”

“…In many kinds of exocrine epithelia, muscarinic stimulation is linked to PLC/IP 3 signaling pathways and releases stored Ca 2þ . The subsequent increase in [Ca 2þ ] i regulates many kinds of Ca 2þ -activated ion channels, including Ca 2þ -activated Cl À channels [24] and K(Ca) channels [23][24][25][26][27][28]. The prostate is no exception to the concept that the male reproductive tract receives abundant innervation from both the sympathetic and parasympathetic divisions.…”