This study determined whether daily cocaine administration initiates a calcium requirement for the increase in extracellular dopamine produced by psychostimulants. The increase in extracellular dopamine induced by perfusion of amphetamine through a microdialysis probe in the nucleus accumbens shell was enhanced in cocaine- relative to saline-pretreated rats. The augmented portion of the ampheta...

Regulation of protein kinase C in the parathyroid gland was investigated by testing the effects of phorbol ester, exogenous phospholipase C, and low and high calcium concentrations on enzyme activity. Treatment of bovine parathyroid cells with phorbol ester, which activates protein kinase C directly, and with phospholipase C, which produces diacylglycerol, an activator of protein kinase C, sign...

Using a model of the extracellular space, we show how external calcium fluctuations, engendered during normal neural activity, can act as a rapid information-bearing signal in nervous systems. We demonstrate that action potentials propagating along a dendrite can induce large peri-dendritic calcium fluctuations, lowering significantly the external calcium available to overlying presynaptic term...

Spinach (Spinacia oleracea, L.) cells in liquid culture release peroxidases. This release is reduced by EGTA and promoted by calcium ions. In a medium deprived of calcium the rate of peroxidase release is low, but immediately after addition of I mM calcium there is a sudden increase of the extracellular peroxidase activity. Extracellular calcium apparently penetrates into the cultured cells rat...

Toma I, Bansal E, Meer EJ, Kang JJ, Vargas SL, Peti-Peterdi J. Connexin 40 and ATP-dependent intercellular calcium wave in renal glomerular endothelial cells. Am J Physiol Regul Integr Comp Physiol 294: R1769–R1776, 2008. First published April 9, 2008; doi:10.1152/ajpregu.00489.2007.—Endothelial intracellular calcium ([Ca ]i) plays an important role in the function of the juxtaglomerular vascul...

The lateral superior olive (LSO) is the primary auditory nucleus for processing of interaural sound level differences, which is one of the major cues for sound localization. During development, survival and maturation of LSO neurons critically depend on synaptic activity and intracellular calcium signaling. Before hearing onset, glutamatergic synaptic inputs from the cochlear nucleus (CN) to th...

The goal of this study was to assess the mechanisms by which the caffeine-sensitive calcium stores of airway smooth muscle cells are refilled. Bovine trachealis cells were loaded with fura 2-AM (0.5 μM) for imaging of cytosolic calcium concentrations ([Ca2+]i) in the inner cytosol. After a first stimulation (S1) with caffeine, the response to a second stimulation (S2) depended on the presence o...

Intracellular free calcium, [Ca2+]i, was studied in platelets of essential hypertensive subjects and normotensive controls under basal conditions and after stimulation with epinephrine, norepinephrine, angiotensin II, ouabain, and thrombin, using the fluorescent calcium indicator quin 2. Basal [Ca2+]i was significantly higher in hypertensive subjects (n = 32) than in normotensive controls (n = ...

The role of calcium in stimulation of the oxyntic cell by histamine and carbamylcholine was studied using a sensitive quantitative cytochemical staining technique that measures oxyntic cell hydroxyl ion production (HIP) as an index of acid secretion. Histamine (10(-17)-10(-14) M), carbamylcholine (10(-12)-10(-9) M), and extracellular calcium (10(-7)-10(-3) M) caused a linear, dose-dependent sti...