Effects of adenosine 5'-triphosphate and growth hormone on cellular H+ transport and calcium ion concentrations in cloned bovine mammary epithelial cells

Abstract

The present experiment was carried out to investigate the effects of exogenous adenosine 5 -triphosphate (ATP) and growth hormone (GH) on cellular H + efflux rate (extracellular acidification rate) and Ca 2+ concentration ([Ca 2+ ] c ) in cloned bovine mammary epithelial cells (bMEC) raised from the mammary gland of a 26-daypregnant Holstein heifer. Perifusion of 2-day cultured cells with a medium containing ATP (10, 100 and 1000 µmol/l) for 30 min caused a significant and concentration-dependent increase in the cellular H + efflux rate. ATP application (100 µmol/l) caused a transient and large increase in [Ca 2+ ] c in all cells. In contrast, perifusion with a medium containing bovine GH at 10, 50 and 250 ng/ml for 30 min caused a significant decrease in the cellular H + efflux rate in a concentration-dependent manner. However, bovine GH application (50 ng/ml) caused a small decrease followed by an increase, in some cases, in [Ca 2+ ] c . In bMEC treated with lactogenic hormones (1 µg/l prolactin, 1 nmol/ml dexamethasone and 5 µg/ml insulin) for 2 days, the increased H + efflux rate induced by ATP was significantly reduced, whereas the negative response induced by GH was inversely and significantly changed to the positive. ] c that were significantly changed in the opposite direction by the treatment with lactogenic hormones. The lactogenic hormone treatment also enhanced GHR transcription, which may change post-receptor signal transduction systems for both agents in the bMEC.

P2Y receptor regulation of sodium transport in human mammary epithelial cells

“…Among these receptors, P2Y 1 , P2Y 2 , P2Y 4 , P2Y 6 , and P2Y 11 couple to G q/11 and activate phospholipase C, resulting in increased inositol 1,4,5-trisphosphate formation and mobilization of intracellular Ca 2ϩ (2,5,8,12,14,15,27,29,29). In the present study, several P2Y receptor mRNA subtypes (P2Y 1 , P2Y 2 P2Y 4 , and P2Y 6 ) were identified in HME cells.…”

Oral administration of uridylic acid increases plasma leptin, but suppresses glucose and non-esterified fatty acid concentrations in rats

“…In pulmonary circulation, uridine nucleotides were shown to cause comparative vasodilatation as adenine nucleotides did (Konduri et al, 2004). Activation of P2Y receptors (one of Gprotein coupled receptors) by ATP caused intracellular calcium metabolism in mammary epithelial cells (Katoh et al, 2001).…”

Suppressing effects of bisphenol A on the secretory function of ovine anterior pituitary cells

“…The method for [Ca 2C ] c measurement was principally the same as that described previously for bovine mammary epithelial cells (Katoh et al, 2001). Briefly, 3-d cultured dispersed cells on a collagen-coated, glassbottomed well (35 mm o.d., Matsunami, Japan) were washed with HEPES-buffered solution (mM) (NaCl, 115; KCl, 5.4; CaCl 2 , 1.3; MgCl 2 , 1.0; NaHCO 3 , 18; glucose, 7.5; HEPES, 20; pH 7.4), incubated with Fluo-3/ AM (1 mM) for 60 min at 37 (C. The cells were washed three times with the solution, and [Ca 2C ] c of individual cells were measured using a confocal laser scanning microscope system (MRC-1024, Bio-Rad, USA) attached to an inverted microscope (Axiovert 100, Zeiss, Germany).…”