P2Y₁ Receptor Activation Enhances the Rate of Rat Pinealocyte-Induced Extracellular Acidification via a Calcium-Dependent Mechanism

Abstract

Pineal gland G-protein coupled P2Y₁ receptors potentiate noradrenaline-induced N′-acetylserotonin production, a long term response which occurs after 5 h incubation. In the current study we show that a short-term effect of stimulation of P2Y₁ receptors is the increase in extracellular acidification rate (ECAR), which is mediated by an increase in intracellular calcium concentration ([Ca²⁺]_i). The pD₂ values for ATP (3.06 ± 0.12)-induced ECAR increase was significantly smaller (p < 0.01) than that for ADP (3.64 ± 0.18), 2MeSATP (3.56 ± 0.02) and 2MeSADP (3.65 ± 0.13). The selective P2Y₁ receptor antagonists A3′P-5′P and A3′P-5′PS inhibited the increase in ECAR-induced by ADP. Clamping [Ca²⁺]_i with BAPTA (30 and 50 µmol/l) led to inhibition of ADP-induced increase in ECAR. Agonist and antagonist data indicate P2Y₁ activation leads to a [Ca²⁺]_i-dependent acidification of the extracellular medium.

Molecular Basis for Defining the Pineal Gland and Pinealocytes as Targets for Tumor Necrosis Factor

“…Pinealocytes were cultured according to Ferreira et al (2003). The glands were removed, cut into small pieces and dissociated with trypsin (0.25%, 37°C, 15 min), followed by mechanical dispersion in the presence of 0.3% trypsin inhibitor in a solution: NaCl 120 mM, KCl 5 mM, NaHCO 3 25 mM, KH 2 PO 4 1.2 mM, and glucose 12 mM; 0.1% w/v bovine serum albumin.…”

Influence of melatonin on the development of functional nicotinic acetylcholine receptors in cultured chick retinal cells

“…In some cases the record of the variation of extracellular acidification rate was more sensitive than the measurement of second messengers (24). In the present study, we characterized the microphysiometric response of nAChRs to acetylcholine in the presence or absence of different selective antagonists.…”

“…The functional response of nAChRs to stimulation was measured by microphysiometry, a method that has been validated for several receptor-transduction pathways involving muscarinic (22), noradrenaline, adenosine-5'-triphosphate (23), and serotonin (24) receptors. In some cases the record of the variation of extracellular acidification rate was more sensitive than the measurement of second messengers (24).…”

Regulação da atividade da glândula pineal por estimulação purinérgica.

“…Na presença do quelante de Ca 2+ BAPTA, a velocidade de acidificação extracelular induzida por ADP é inibida, bem como na presença dos antagonistas seletivos P2Y1, adenosina 3′, 5′-bifosfato (A3'P5'P) e adenosina 3'-fosfato-5'-fosfosulfato (A3'P5'PS) (Ferreira et al, 2003). et al, 1996).…”