Intracellular free-calcium concentration ([Ca2+]i) was measured in lamprey spinal axons using the fluorescent calcium indicator fura 2. We used both a photomultiplier tube and a video-image processing system to measure the temporal and spatial distributions of [Ca2+]i in the proximal segments of transected axons. Within 3 min following transection, a spatially graded increase in the [Ca2+]i was...

An acute increase in tubular fluid flow rate in the microperfused cortical collecting duct (CCD), associated with a approximately 20% increase in tubular diameter, leads to an increase in intracellular Ca2+ concentration ([Ca2+]i)in both principal and intercalated cells (Woda CB, Leite M Jr, Rohatgi R, and Satlin LM. Am J Physiol Renal Physiol 283: F437-F446, 2002). The apical cilium present in...

We have studied the effects of gamma-aminobutyric acid (GABA) and of reducing the Cl- gradient on the [Ca2+]i in pyramidal neurons of rat somatosensory cortex. The Cl- gradient was reduced either with furosemide or by oxygen-glucose deprivation. Immature slices taken at postnatal day (P)7-14 were labeled with fura-2, and [Ca2+]i was monitored in identified pyramidal cells in layer II/III as the...

We investigated the neuroprotective properties of two M-type K+ channel blockers, linopirdine and its analog XE991, in rat sympathetic neurons deprived of nerve growth factor (NGF). Linopirdine and XE991 promoted sympathetic neuronal survival 48-72 hr after NGF withdrawal in a concentration-dependent manner. Both drugs prevented neuronal apoptosis by blocking the pathway leading to the release ...

Experiments were conducted to gain insight into mechanisms responsible for exaggerated renal vascular reactivity to ANG II and vasopressin (AVP) in spontaneously hypertensive rats (SHR) during the development of hypertension. Cytosolic calcium concentration ([Ca2+]i) was measured by ratiometric fura 2 fluorescence and a microscope-based photometer. Vascular smooth muscle cells (SMC) from preglo...

The inhibitory effects of calcium antagonists on high-potassium or glutamate (Glu) enhanced intracellular calcium ion ([Ca2+]i) levels were studied in cultured cerebellar granule cells. Dosages between 0.5 and 10 microM of flunarizine, nicardipine, SM6586 and SM12565 reduced the rise in [Ca2+]i induced by 50 mM KCl in a dose-dependent manner, although diltiazem, verapamil and nifedipine showed ...

Protein phosphorylation and cytosolic-free [Ca2+] ([Ca2+]i) contribute to signalling cascades evoked by the water-stress hormone abscisic acid (ABA) that lead to stomatal closure in higher-plant leaves. ABA activates an inward-rectifying Ca2+ channel at the plasma membrane of stomatal guard cells, promoting Ca2+ entry by shifting the voltage-sensitivity of the channels. Because many of these ef...

Endothelium-dependent vasodilators, nitrates, and atrial natriuretic factor relax blood vessels by increasing vascular cyclic guanosine monophosphate (cGMP). The mechanisms by which cGMP relaxes vascular smooth muscle (VSM) are not known. Since contraction of VSM is associated with increased intracellular calcium and pH, we hypothesized that cGMP may decrease vascular tone by lowering ionized, ...

BACKGROUND Ketamine was previously suggested to relax vascular smooth muscle by reducing the intracellular Ca2+ concentration ([Ca2+]i). However, no direct evidence is available to indicate that ketamine reduces the [Ca2+]i in vascular smooth muscle of systemic resistance arteries. METHODS Endothelium-intact or -denuded smooth muscle strips were prepared from rat small mesenteric arteries. Is...

The early stages of weight loss are associated with a reduction in blood pressure, and the mechanisms mediating this reduction remain unclear. Platelet free calcium levels, [Ca2+]i, have been reported to be elevated in essential hypertension and to decrease with pharmacological treatment of the hypertension. In the current study, 18 obese subjects had measurements of blood pressure, forearm blo...