Regulation of Ryanodine Receptor–Mediated Ca2+ Release in Vas Deferens Smooth Muscle Cells

Abstract

Abstract. Ca2+ release from intracellular store sites via the ryanodine receptor (RyR) and hormonal regulation by flutamide, an androgen-receptor (AR) antagonist, on it were examined in vas deferens (VD) smooth muscle cells (SMCs). VD and VDSMCs were obtained from two groups of male rats that were treated p.o. with 100 mg/kg flutamide (Flu) or vehicle (Vehicle). Both spontaneous and caffeine-induced Ca 2+ releases were markedly smaller in single VDSMCs from Flu than in those from Vehicle. Interestingly, [Ca 2+ ] i rise by 100 μM norepinephrine in VDSMCs from Flu was larger than that in those from Vehicle. The contractions induced by direct electrical stimulation in tissue preparations from Flu showed lower susceptibility to 30 μM ryanodine than those from Vehicle. Real-time PCR analyses revealed that the transcripts of ryanodine receptor (RyR) type 2 and type 3 (RyR2 and RyR3) were expressed in VD and markedly reduced in Flu. The protein expression of total RyR was significantly reduced by flutamide treatment, but that of inositol 1,4,5-trisphosphate receptor (IP3R) was not affected. It can be strongly suggested that long term block of AR by flutamide reduced the expression of RyR and its contribution to the contraction, but not those of IP3R in VDSMCs.

Castration Induces Down-Regulation of A-Type K+ Channel in Rat Vas Deferens Smooth Muscle

“…Single SMCs were enzymatically isolated from VD of male Wistar rats (7 week-old) using previously reported method [7,27]. As previously reported, we confirmed that VDSMCs were morphologically elongated and induced contraction and intracellular Ca 2+ elevation by application of 100 µM norepinephrine, as reported previously [39,40]. Whole-cell voltage clamping was applied to single cells with patch pipettes, using a CEZ-2400 amplifier (Nihon Kohden, Tokyo, Japan).…”

Ca2+-mediated Mitochondrial Reactive Oxygen Species Metabolism Augments Wnt/β-Catenin Pathway Activation to Facilitate Cell Differentiation

“…3 A, 0.5h, arrows ). Similarly, a 1-h treatment of proliferating cells with 1 m m CAF, which stimulates Ca 2+ release from the ER stores via the ryanodine receptors ( 35 , 36 ), strongly decreased the signal ( Fig. 3 B ).…”

Minding the calcium store: Ryanodine receptor activation as a convergent mechanism of PCB toxicity

“…The patterns of expression of RyR isoforms is highly dependent on the type of smooth muscle and multiple isoforms can be expressed within a smooth muscle cell (Chalmers, Olson, MacMillan, Rainbow, & McCarron, 2007). For example, recent RT-PCR results have indicated that RyR2 and RyR3 are expressed in cultured myocytes from rat mesenteric artery (Berra-Romani, Mazzocco-Spezzia, Pulina, & Golovina, 2008) or vas deferens (Ohno, Ohya, Yamamura, & Imaizumi, 2009), although the ratio of the two isoforms can change with proliferation. In contrast, uterine smooth muscle expresses two splice variants of RyR3 that are differentially expressed in nonpregnant and pregnant myometrium, although their functional significance has been recently questioned (Noble, Matthew, Burdyga, & Wray, 2009).…”