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The reverse hemolytic plaque assay (RHPA) was used to study the secretory properties of single rat pancreatic B cells, and to identify insulin-secreting cells for patch-clamp experiments. In secretion studies using the RHPA, we find that the percentage of secreting B cells and the amount of insulin secreted per B cell increase as the glucose concentration(More)
We studied the effects of nerve growth factor (NGF), fibroblast growth factor (FGF), and dibutyryl-cAMP (dbcAMP) on rat pancreatic β-cell morphology and of NGF and dbcAMP on insulin secretion. After 2 wk in culture, nearly 3% of β-cells extended neurite-like processes spontaneously; when cells were treated with NGF, almost 30% of them extended processes. In(More)
The action of exogenous ATP on cytoplasmic free Ca2+ ([Ca2+]i) was studied in insulin secreting cells using fura-2. Stimulation of clonal pancreatic beta-cells (HIT) with ATP (range 2-20 microM) evoked a sustained elevation in [Ca2+]i. ATP selectively promoted Ca2+ influx and not Ca2+ mobilization since (1) the effect required external Ca1+ and (2) was(More)
Human studies have shown that chronic inorganic arsenic (iAs) exposure is associated with a high prevalence and incidence of type 2 diabetes. However, the mechanism(s) underlying this effect are not well understood, and practically, there is no information available on the effects of arsenic on pancreatic beta-cells functions. Thus, since insulin secreted(More)
Differentiation and function of pancreatic beta cells are regulated by a variety of hormones and growth factors, including nerve growth factor (NGF). Whether this is an endocrine or autocrine/paracrine role for NGF is not known. We demonstrate that NGF is produced and secreted by adult rat pancreatic beta cells. NGF secretion is increased in response to(More)
Insulin secretion in mature beta-cells increases vigorously when extracellular glucose concentration rises. Glucose-stimulated insulin secretion depends on Ca(2+) influx through voltage-gated Ca(2+) channels. During fetal development, this structured response is not well established, and it is after birth that beta-cells acquire glucose sensitivity and a(More)
We investigated short-term in vivo and in vitro effects of streptozotocin (STZ) on pancreatic beta cells. Male Wistar rats were treated with 75 mg/kg STZ, and, after 4 hrs blood glucose and insulin were measured and islet cells were isolated, cultured for 16 hrs, and challenged with 5.6 and 15.6 mM glucose. Treated rats showed hyperglycemia (approximately(More)
Chronic exposure to high concentrations of arsenic in drinking water is associated with an increased risk for developing type 2 diabetes. The present revision focuses on the effect of arsenic on tissues that participate directly in glucose homeostasis, integrating the most important published information about the impairment of the expression of genes(More)
In the present study we have used a reverse hemolytic plaque assay and frequency distribution analysis to characterize the insulin secretory response of individual rat pancreatic B-cells in culture. Heterogeneous secretory behavior was observed with a multimodal distribution, suggesting the existence of B-cell subpopulations. Insulin secretion in response(More)
The metabolism of beta-L-glucose pentaacetate and its interference with the catabolism of L-[U-14C]glutamine, [U-14C]palmitate, D-[U-14C]glucose, and D-[5-3H]glucose were examined in rat pancreatic islets. Likewise, attention was paid to the effects of this ester on the biosynthesis of islet peptides, the release of insulin from incubated or perifused(More)