Potassium currents regulating secretion from Brunner's glands in guinea pig duodenum

This study examined the role of outward K(+) currents in the acinar cells underlying secretion from Brunner's glands in guinea pig duodenum. Intracellular recordings were made from single acinar cells in intact acini in in vitro submucosal preparations, and videomicroscopy was employed in the same preparation to correlate these measures with secretion. Mean resting membrane potential was -74 mV and was depolarized by high external K(+) (20 mM) and the K(+) channel blockers 4-aminopyridine (4-AP), quinine, and clotrimazole. The cholinergic agonist carbachol (60-2,000 nM; EC(50) = 200 nM) caused a concentration-dependent initial hyperpolarization of the membrane and an associated decrease in input resistance. This hyperpolarization was significantly decreased by 20 mM external K(+) or membrane hyperpolarization and increased by 1 mM external K(+) or membrane depolarization. It was blocked by the K(+) channel blockers tetraethylammonium (TEA), 4-AP, quinine, and clotrimazole but not iberiotoxin. When videomicroscopy was employed to measure dilation of acinar lumen in the same preparation, carbachol-evoked dilations were altered in a parallel fashion when external K(+) was altered. The dilations were also blocked by the K(+) channel blockers TEA, 4-AP, quinine, and clotrimazole but not iberiotoxin. These findings suggest that activation of outward K(+) currents is fundamental to the initiation of secretion from these glands, consistent with the model of K(+) efflux from the basolateral membrane providing the driving force for secretion. The pharmacological profile suggests that these K(+) channels belong to the intermediate conductance group.     

Effect of ayurvedic medicines on beta-glucuronidase activity of Brunner's glands during recovery from cysteamine induced duodenal ulcers in rats

Biochemical and histochemical studies revealed decreased beta-glucuronidase activity in the Brunner's glands of duodenal ulcerated rats. The enzyme activity showed gradual increase during recovery. Rats treated with a mixture of Ayurvedic medicines (Glycyrrhiza glabra, Terminalia chebula, Piper longum and Shanka Bhasma) recovered faster with concomitant increase in beta-glucuronidase activity in the Brunner's glands. It can be concluded that Ayurvedic medicines used do not act as antacid but improve the secretory status of Brunner's glands involved in the protection against duodenal ulcer.     

Exocrine secretion of epidermal growth factor from Brunner's glands. Stimulation by VIP and acetylcholine

Brunner's glands of the duodenum are innervated by cholinergic and VIP-ergic nerves, and the glands have been shown to contain epidermal growth factor (EGF). In this study the effect of VIP and acetylcholine (Ach) on secretion of EGF from Brunner's glands was investigated in the rat. Intravenous infusion of VIP stimulated the flow rate of duodenal secretion, an effect which was inhibited by atropine. Ach alone did not significantly increase flow rate, and combined infusion of VIP and Ach induced the same flow as VIP alone. Concentration of EGF in duodenal secretion was increased by infusion of Ach, and this effect was potentiated by VIP. Infusion of VIP alone did not influence EGF concentration. EGF output from Brunner's glands was significantly stimulated by i.v. infusion of VIP and of Ach and combined infusion further increased EGF output. The study has demonstrated exocrine secretion of EGF from Brunner's glands, and it is suggested that stimulation is mediated by interaction of neuronal VIP and Ach.     

Mucosubstance histochemistry of Brunner's glands, pyloric glands and duodenal goblet cells in the ferret

The mucosubstance of Brunner's glands, pyloric glands and duodenal goblet cells were studied using the various histochemical methods. The secretions of both Brunner's and pyloric glands were similar in their histochemical reactions. They contained neutral mucosubstances as in these glands in man. The duodenal goblet cells showed variations in their histochemical characters. (i) The secretions of most of the deep cells and the majority of superficial cells contained sialidase-labile and sialidase-resistant sialomucins. (ii) There were a few superficial and occasional deep cells, the secretions of which contained sulphated mucosubstances. (iii) There were some goblet cells, more in the villi than in the crypts, the secretions of which contained a mixture of sialomucins and a sulphated mucin. The sialomucin was mostly sialidase-labile and partly sialidase-resistant.     

Mucosubstance histochemistry of Brunner's glands,pyloric glands and duodenal goblet cells in the ferret

Summary The mucosubstance of Brunner's glands, pyloric glands and duodenal goblet cells were studied using the various histochemical methods.The secretions of both Brunner's and pyloric glands were similar in their histochemical reactions. They contained neutral mucosubstances as in these glands in man.The duodenal goblet cells showed variations in their histochemical characters. (i) The secretions of most of the deep cells and the majority of superficial cells contained sialidase-labile and sialidase-resistant sialomucins. (ii) There were a few superficial and occasional deep cells, the secretions of which contained sulphated mucosubstances. (iii) There were some goblet cells, more in the villi than in the crypts, the secretions of which contained a mixture of sialomycins and a sulphated mucin. The sialomucin was mostly sialidase-labile and partly sialidase-resistant.     

Adenocarcinoma of Brunner's glands in a baboon (Papio cynocephalus)

A spontaneous neoplasm in an adult female baboon (Papio cynocephalus) was characterized by glandular formation, production of extracellular mucus, and focal invasion of the duodenal wall and pancreas. The tumor was diagnosed as a mucus-secreting adenocarcinoma of Brunner's glands.     

Amylase release from rat parotid glands II. Calcium kinetics

The kinetics of ⁴⁵Ca²⁺ uptake, efflux, and calcium potentiation of amylase release by slices of rat parotid glands were examined. Pretreatment of the tissue with 11.25 mM ⁴⁵Ca²⁺ medium increased the total tissue ⁴⁵calcium content. Lanthanum (1 mM) decreased tissue uptake, blocked the slow components of exchange and appeared to inhibit transcellular calcium movement. Neither dibutyryl cyclic AMP nor caffeine caused consistently significant effects on ⁴⁵Ca²⁺ kinetics, or total ⁴⁵calcium content. Carbamylcholine increased the initial rate of ⁴⁵Ca²⁺ uptake, but had no effect on total uptake.Elevation of the extracellular Ca²⁺ concentration to 11.25 mM during stimulation of amylase release resulted in an initial decrease in the rate of amylase release followed by a potentiation of release which developed slowly, requiring 40–50 min to reach the maximal response.The inability to detect release-related changes in either calcium influx or mobilization, and the lengthy times and high Ca²⁺ concentrations required to achieve calcium potentiation suggests that calcium does not couple amylase release.