There is controversy as to whether platelet intracellular free calcium ([Ca2+]i) is increased in spontaneously hypertensive rats (SHR) as compared with Wistar-Kyoto (WKY) rats. Discrepant results may be due to methodological problems including platelet activation during the collection process and leakage of intracellular dye used for [Ca2+]i measurement. To provide further insight into this pro...

Aortic smooth muscle isolated from spontaneously hypertensive rats (SHR) and normotensive, age-matched Wistar Kyoto rats (WKY) was precontracted by potassium chloride. The relaxant effect of nifedipine (NIF) was much more pronounced in SHR than in WKY, while the relaxation produced by nitroglycerin (NTG) was similar in both tissues. EC50s were (in - log [M]) NIF:SHR 13.1 +/- 0.4 and WKY 9.4 +/-...

The abnormal intestinal Ca2+ transport reported in spontaneously hypertensive rats (SHR) has been attributed to decreased responsiveness to calcitriol. We reexamined this hypothesis by studying the calcitriol regulation of SHR duodenal calbindin-D9K and calmodulin and the relation of calcitriol to Ca2+ uptake by isolated enterocytes. SHR and normotensive Wistar-Kyoto (WKY) rats were injected wi...

The effects of physiological levels of glucagon on Ca2+ efflux were examined in the perfused rat liver. Two methods were used to estimate Ca2+ efflux: prior labeling of the calcium pools with 45Ca2+ and measurement of perfusate Ca2+ with atomic absorption. According to both methods, glucagon administration at the physiological level evoked Ca2+ release. The released Ca2+ originated mostly from ...

We hypothesized that endotoxin would impair agonist-induced calcium (Ca2+) mobilization in rat mesangial cells, owing to the induction of nitric oxide synthase (NOS) and augmented nitric oxide (NO) synthesis. We measured basal and bradykinin-induced peak free cytosolic Ca2+ concentrations through microspectrofluorimetry with fura-2 in confluent mesangial cells, and assayed conditioned medium fo...

Loading isolated rat hepatocytes with high concentrations of the fluorescent Ca2+-chelator quin-2 in the absence of extracellular Ca2+ decreases by about 3-fold the cytosolic Ca2+ concentration ([Ca2+]i). In these low [Ca2+]i cells, the initial 45Ca2+ uptake rate, assumed to represent the Ca2+ influx, is stimulated to a level close to that promoted by maximal doses of vasopressin and angiotensi...

The effects of anoxia were studied in freshly isolated rat hepatocytes maintained in agarose gel threads and perfused with Krebs-Henseleit bicarbonate buffer (KHB). Cytosolic free calcium (Ca2+i) was measured with aequorin, intracellular sodium (Na+i) with SBFI, intracellular pH (pHi) with BCECF, lactic dehydrogenase (LDH) by the increase in NADH absorbance during lactate oxidation to pyruvate,...

Correlative studies on transports of Ca2+ and Na+ and the properties of Ca2+ transport were carried out in rat kidney cortex slices. Ouabain had no effect on the Ca2+ transport but did inhibit the Na+ transport extensively. With addition of 2,4-dinitrophenol to the incubation medium, or under the anaerobic conditions, the effluxes of Ca2+ and Na+ were inhibited while the Ca2+ influx was enhance...

Using capacitance measurements and the single-cell immunoblot assay to study secretion in dorsal root ganglion neurons, we found that the somata underwent robust exocytosis upon depolarization and released substance P, in response to KCl stimulation. The parallel changes between capacitance responses and intracellular Ca2+ concentration ([Ca2+]i) at different membrane potentials and the inhibit...

Myocardial generation of insulin-like growth factor-1 (IGF-1) is altered in hypertrophy and heart failure, but there are no reports on acute functional effects of IGF-1 in human cardiac muscle. We examined inotropic responses and signal transduction mechanisms of IGF-1 in human myocardium. Experiments were performed in isolated trabeculae or cardiomyocytes from 46 end-stage failing hearts. The ...