Heterogeneity of acid secretion induced by carbachol and histamine along the gastric gland axis and its relationship to [Ca2+](i)
ABSTRACT The gastric glands of the mammalian fundic mucosa are constituted by different cell types. Gastric fluid is a mixture of acid, alkali, ions, enzymes, and mucins secreted by parietal, chief, and mucous cells. We studied activation of acid secretion using LysoSensor Yellow/Blue in conjunction with fluo 3 to measure changes in pH and Ca(2+) in isolated rabbit gastric glands. We evidenced a spatial heterogeneity in the amplitude of acid response along the gland axis under histamine and cholinergic stimulation. Carbachol induced a transitory pH increase before acidification. This relative alkalinization may be related to granule release from other cell types. Omeprazole inhibited the acid component but not the rise in pH. Histamine stimulated acid secretion without increase of lumen pH. We studied the relationship between Ca(2+) release and/or entry and H(+) secretion in glands stimulated by carbachol. Ca(2+) release was associated with a fast and transient components of H(+) secretion. We found a linear relationship between Ca(2+) release and H(+) secretion. Ca(2+) entry was associated with a second slow and larger component of acid secretion. The fast component may be the result of activation of Cl(-) and K(+) channels and hence H(+)/K(+) pumps already present in the membrane, whereas the slow component might be associated with translocation of H(+)/K(+) pumps to the canaliculi. In conclusion, with cholinergic stimulation, gastric glands secrete a mixture of acid and other product(s) with a pH above 4.2, both triggered by Ca(2+) release. Maintenance of acid secretion depends on Ca(2+) entry and perhaps membrane fusion.
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ABSTRACT: Over production of gastric acid in response to various stimuli is responsible for peptic ulceration in majority of patients. Calcium plays an important role in the release of various stimulant mediators. The aerial part of Carthamus tinctorius L. are reported to have calcium channel blocking activity. This study was designed to find out the effects of extract on the volume and acidity, free and total, of Carbachol induced gastric secretion and to compare the results with that of Cimetidine and Verapamil on the same parameters. The animals were kept on fasting for 48 h after which the pylorus of each animal was ligated. The extract was administered 200 and 400 mg/kg of body weight, Cimetidine 2.5 mg/kg and Carbachol 600 μg/kg and Verapamil 10 mg/kg body weight, intraperitoneally, in pylorus ligated rats. It was found that the extract reduced the volume, free and total acidity of gastric secretion, which were statistically highly significant when compared with Carbachol (P < 0.001). Cimetidine also had the same effects. When the difference of mean values, brought about by extract, was compared with those of Cimetidine, it was found that these differences in the volume and free acidity were significant indicating that Cimetidine is more effective than the extract. The extract can, however, be used effectively in the treatment of peptic ulcer. Although, the extract reduced gastric acidity significantly, but is less effective than CimetidineOriental Pharmacy and Experimental Medicine 12/2011; 11(4). DOI:10.1007/s13596-011-0041-3
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ABSTRACT: The Cepstral analysis is proposed with Gaussian Mixture Models (GMM) method to classify respiratory sounds in two categories: normal and wheezing. The sound signal is divided in overlapped segments, which are characterized by a reduced dimension feature vectors using Mel-Frequency Cepstral Coefficients (MFCC) or subband based Cepstral parameters (SBC). The proposed schema is compared with other classifiers: Vector Quantization (VQ) and Multi-Layer Perceptron (MLP) neural networks. A post processing is proposed to improve the classification results.Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2004; 1:9-12. DOI:10.1109/IEMBS.2004.1403077
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ABSTRACT: This review summarizes the last year's literature regarding the regulation and measurement of gastric exocrine and endocrine secretion. Parietal cells, distributed along much of the length of the oxyntic glands, with highest density in the neck and base, secrete HCl as well as transforming growth factor-alpha, amphiregulin, heparin-binding epidermal growth factor-like growth factor, and sonic hedgehog. Acid facilitates the digestion of protein and absorption of iron, calcium, vitamin B(12) as well as prevents bacterial overgrowth, enteric infection, and possibly food allergy. The major stimulants of acid secretion are gastrin, histamine, and acetylcholine. Ghrelin and orexin also stimulate acid secretion. The main inhibitor of acid secretion is somatostatin. Nitric oxide and dopamine also inhibit acid secretion. Although Helicobacter pylori is associated with duodenal ulcer disease, most patients infected with the organism produce less than normal amount of acid. The cytoskeletal proteins ezrin and moesin participate in parietal cell acid and chief cell pepsinogen secretion, respectively. Despite our vast knowledge, the understanding of the regulation of gastric acid secretion in health and disease is far from complete. A better understanding of the pathways and mechanisms regulating acid secretion should lead to improved management of patients with acid-induced disorders as well as those who secrete too little acid.Current opinion in gastroenterology 10/2009; 25(6):529-36. DOI:10.1097/MOG.0b013e328331b62a · 3.66 Impact Factor