The Relationship between Spontaneous Calcium Oscillations and Cell Proliferation in Cultured Smooth Muscle Cells.

Abstract

ABSTRACT- (9) reported that the growth of DDT,MF-2 smooth muscle cells was suppressed by thapsigargine, an intracel lular Ca 21 pump inhibitor, which also suppressed spon taneous calcium oscillations in our cultured smooth mus cle cells (7). These reports prompted us to investigate the relationship between the spontaneous Ca2+ oscillations and cell proliferation in the culture cells. Here, we ex amined the effects of BAPTA, caffeine, thapsigargine and La3+, which all suppress Ca2+ oscillations, on cell proliferation. The longitudinal muscle segments of small intestine were obtained from male guinea pig as described previous ly (7) and then cut into small pieces. Small explants of lon gitudinal muscle were cultured in minimum essential me dium (MEM; Gibco, Gaithersburg, MD, USA) containing 20% fetal calf serum on 25-mm-diameter glass coverslips inside 35-mm Petri dishes and maintained at 37 °C under humidified conditions of 95 % air 5 % CO2. After 24 hr, the culture medium was replaced with MEM containing 10% fetal calf serum, and the medium was changed after 4 days in culture. Cells began to grow out from the ex plants after 4 days in culture. Cells cultured for 6 to 7 days were used in the experiments. [Ca 21]i was measured by using a digital video imaging system and fura-2 in MEM containing 12.5 mM HEPES, pH 7.4, as described previously (7). The imaging system consisted of a Nikon Diaphoto TMD fluorescence microscope (Tokyo); CAM 230 (Japan Spectroscopic Co., Tokyo), a dual wavelength fluorescence excitator; an intensified CCD camera, C2400-87; and an image analyzer, ARGUS-50

Interleukin-1β Induces Calcium Transients and Enhances Basal and Store Operated Calcium Entry in Human Myometrial Smooth Muscle1

“…Both responses were sensitive to La 3ϩ at concentrations reported to block storeoperated and agonist-induced, nonstore-operated Ca 2ϩ entry [25][26][27][28][29], and the effect of La 3ϩ on basal Ca 2ϩ entry was similar to that of [Ca 2ϩ ] o removal. This infers that generation of spontaneous Ca 2ϩ transients is related to stimulation of basal Ca 2ϩ entry and supports previous observations regarding the dependence of Ca 2ϩ spikes in cultured myometrium [30] and other smooth muscle types [31,32] on Ca 2ϩ entry. In A7r5 cells (a vascular smooth muscle cell line), spontaneous Ca 2ϩ oscillations appear to involve voltage-gated Ca 2ϩ entry [33]; however, in the present study, L-and T-type Ca 2ϩ -channel activity was not detectable in the HMSM cells.…”

Intracellular Ca2+ regulation in a human prostate stromal cell culture

“…We suggest that phenylephrine releases Ca 2þ from intracellular stores because: Ca 2þ transients were evoked in Ca 2þ -free superfusate, when Ca 2þ in£ux through Ca 2þ channels would have been abolished [Sui et al, 2004]; phenylephrine did not generate a Ca 2þ transient immediately after ca¡eine raised [Ca 2þ ] i , presumably as they both release Ca 2þ from a similar intracellular store. Spontaneous rises of intracellular Ca 2þ were observed, as in other cultured myocytes [Kawanishi et al, 1994;Wu et al, 1996], that were not driven primarily by Ca 2þ in£ux via L-type Ca 2þ channels, as they were resistant to verapamil. Suppression of these transients by ca¡eine suggests that they arise as spontaneous Ca 2þ release from intracellular stores.…”

“…The functional role of these Ca 2þ -transients is unclear; but in several cell types, similar transients have been implicated in cell division, di¡erentiation, and growth [Kawanishi et al, 1994;Gu and Spitzer, 1995;Watt et al, 2000]. The increased incidence of Ca 2þ -transients in prostate stromal cells with a phenylephrine response, may suggest a regulation over cell di¡erentiation by a 1 -adrenoceptor activation.…”

Muscarinic receptor‐induced calcium responses in astroglia

“…The amplitude, frequency, and duration of calcium responses are important intracellular signals in many cells, regulating transcription factor activation and cell differentiation (43,44). Calcium has also been shown to mediate the proliferation of many cell types, including glial cells (45)(46)(47). The characterization and quantitation of calcium responses, therefore, will allow the study of pharmacological and toxicological agents on this response.…”