Effect of tetanus toxin on noradrenalin liberation from rat brain synaptosomes

A purified preparation of tetanus toxin (TT) (80–800 MLD/mg protein) was shown to induce liberation of both endogenous and exogenous (labeled with¹⁴C) noradrenalin (NA) from isolated nerve endings (synaptosomes) of the rat brain. Within the range of concentrations studied TT does not inhibit secretion of NA evoked by depolarization of synaptosomes by different methods in vitro.Laboratory of General Pathology of the Nervous System, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 2, pp. 148–150, February, 1980.     

Effect of Atropine and SC-15396 on Stimulated Gastric Acid Secretion in the Atlantic Cod,Gadus morhua

Gastric acid secretion was measured in swimming codfish surgically equipped with a catheter draining the stomach. Gastric acid secretion was stimulated by histamine (5 or 15μg/kg-h) or by carbachol (5μg/kg-h). Pretreatment with atropine (1 μmol/kg-h) completely prevented the acid secretion induced by carbachol, but did not influence the secretion induced by histamine. Atropine had marked effects on the motor functions of the stomach, and seriously reduced the volume draining from the stomach. Infusion of phenol red indicated that the decrease in volume was due to a decrease in recovery of ingested water. SC-15396, “antigastrin”, significantly depressed acid secretion induced by histamine, and reduced carbachol-stimulated secretion, although the latter was statistically insignificant. The effects of SC-15396 is discussed with reference to the absence of receptors for gastrin related to gastric acid secretion in the codfish stomach.     

Effects of enkephalins and their analogs on gastric secretion

The effects of enkephalin analogs on gastric secretion were studied. It was found that gastric secretion stimulated by histamine was significantly increased under the influence of the enkephalin analog Tyr-D-Ala-Gly-Phe-(NO₂)NH₂. The enkephalin analog Tyr-Gly-Gly-Phe-Leu-D-Arg increased the amount of gastric juice and the secretion of pepsin, but the hydrochloric acid debit was lower than in experiments with perfusion of histamine alone. Another enkephalin analog, Tyr-D-Ala-Gly-Phe-D-Leu-Arg, introduced simultaneously with histamine, significantly lowered the secretion of gastric juice only 90–105 min after the beginning of perfusion.Translated from Fiziologicheskii Zhurnal SSSR imeni I. M. Sechenova, Vol. 68, No. 5, pp. 632–638, May, 1982.     

Clinical anatomy of the peritoneal mesothelium: A review

This paper reviews the structure, function, and clinical significance of peritoneal mesothelium, once thought to be a passive membrane, but now known to play an active role in exchanges between the peritoneal cavity and the blood. The advent of continuous ambulatory peritoneal analysis (CAPD) has revived interest in the peritoneum, whose ultrastructure is much changed by CAPD. Studies of the healing of mesothelium have shown that the new mesothelium develops from subperitoneal perivascular connective tissue cells, and not by a process of centripetal growth from the wound margins as in the healing of other epithelial surfaces. Peritoneal mesothelial cells possess fibrinolytic properties, which may be important in preventing fibrinous adhesions from being converted to permanent fibrous adhesions, which may cause intestinal obstruction. Mesothelium also produces prostacyclin. These properties have led to the use of mesothelium as a substitute for endothelium, both for coating prosthetic vascular grafts, and also in peritoneal tube grafts for replacing segments of vein. The resurgence of interest in the peritoneal mesothelium provides a stimulus for clinician and anatomist to cooperate in further exploration of its clinical potential.     

Actions of somatostatin on perfused bovine adrenal glands and cultured bovine adrenal medullary cells

The effects of somatostatin on catecholamine secretion and inositol phosphate accumulation have been studied using isolated perfused bovine adrenal glands and cultured bovine adrenal medullary cells. Somatostatin had no effect on basal adrenaline or noradrenaline secretion from either preparation. At concentrations above 1 microM, somatostatin inhibited the secretion of both catecholamines induced by 5 microM nicotine from cultured chromaffin cells. In contrast, over the concentration range 0.1 nM-10 microM, somatostatin had no effect on the secretory responses produced by 10 nM angiotensin II or 1 microM histamine. Inositol phosphate accumulation in cultured bovine adrenal medullary cells was unaffected by 0.1 nM-0.1 microM somatostatin, however at 1 and 10 microM somatostatin it was significantly increased, by 23% and 103% respectively. The effects of somatostatin (0.1 nM-10 microM) and of 50 microM muscarine on inositol phosphate accumulation were simply additive. Similarly, somatostatin at 0.1 nM and 10 nM together with 10 nM angiotensin II or 1 microM histamine produced additive inositol phosphate responses. In contrast, 1 microM somatostatin gave significantly more-than-additive (synergistic) inositol phosphate responses with angiotensin II and histamine. The results suggest that some adrenal medullary cells possess several types of receptors, and that these receptors may interact to produce non-additive responses.     

Studies on the gastric anti-ulcer activity of hypolaetin-8-glucoside

The gastric anti-ulcer activity of hypolaetin-8-O-β-D -glucoside (H-8-G), a flavonoid isolated from Sideritis leucantha, has been studied in rats. This compound significantly reduced gastric lesions induced by ethanol or acetylsalicylic acid (ASA), with an increase in mucus production. In the pylorus-ligated rat, H-8-G did not affect the volume of gastric secretion but decreased its acidity and peptic activity. The anti-ulcer activity of this flavonoid does not depend on stimulation of cell proliferation in the rat gastric mucosa. Our results suggest that H-8-G activity is related to its cytoprotective effects [mediated by endogenous prostaglandins (PGs) and associated to an increase in gastric mucus production] alongside with its moderate antisecretory effects.     

Transient Effect of the Combination of Insulin and Sulfonylurea (Glibenclamide) on Glycemic Control in Non-Insulin Dependent Diabetics Poorly Controlled with Insulin Alone

ABSTRACT In a double-blind cross-over study we compared the effects of insulin plus glibenclamide, 5 mg twice daily, with insulin plus placebo during 8-week periods on metabolic parameters in 13 non-insulin dependent diabetic (NIDDM) patients poorly controlled with insulin alone. The combination therapy improved diabetic control as assessed by fasting blood glucose (p<0.001), 24-hour urinary glucose (p<0.01) and glycohemoglobin (HbA₁) concentrations (p<0.05 at week 12). The effect tended to cease with time. Significantly higher C-peptide values were found during combination treatment than during insulin-placebo (p<0.01) and the changes in fasting C-peptide concentrations correlated positively with the changes in HbA₁ concentrations (r=0.56, p<0.05). There was no difference in glucagon concentrations, insulin binding to erythrocytes or insulin sensitivity between the two study periods. Neither did the combination therapy influence blood lipids significantly. The present study shows that the combination of insulin and glibenclamide may be of limited value in the treatment of NIDDM patients poorly controlled with insulin alone. However, thus far the long-term results are uncertain. In the absence of significant effects on insulin binding and insulin sensitivity, the improved diabetic control seems to be explained, at least partly, by glibenclamide-induced stimulation of insulin secretion.     

Cyclic nucleotide content and phosphodiesterase activity in the rds mouse (020/A) retina

Cyclic nucleotide metabolism was examined in the retina and in the retinal pigment epithelium (RPE)-choroid complex of the rds mouse (020/A), a mutant in which discrete photoreceptor outer segment disc structures fail to develop. In retinas of both rds and control (Balb/c) mice, cyclic AMP levels peak at 10-15 days (20-25 pmol mg-1 protein). The level drops to about 10 pmol mg-1 at about one month in normal retinas but remains high in affected retinas. Cyclic GMP levels increase five-fold in Balb/c retinas as ROS develop whereas, in affected retinas, the levels remain constant and low (about 5 pmol mg-1). In RPE-choroid, cyclic nucleotide levels are similar in control and affected mice. Cyclic AMP phosphodiesterase (PDE) activity is somewhat higher in affected than in control retinas; conversely, cyclic GMP-PDE is lower. Both cyclic AMP-PDE and cyclic GMP-PDE activities are different in normal and affected RPE-choroid. Thus, although the rds (020/A) mouse belongs to the early-onset photoreceptor dysplasia group of hereditary retinal degenerations on a morphological basis, it does not exhibit high retinal cyclic GMP levels and thus appears to be distinct from other animals exhibiting early postnatal photoreceptor dysfunction.     

The role of serotonin in mucociliary transport system in the ciliated epithelium of frog palatine mucosa

The effects of serotonin (5-hydroxytryptamine, 5-HT) on mucociliary transport and mucus secretion were investigated pharmacologically. The presence of 5-HT in the ciliated epithelium of frog palatine mucosa was examined chromatographically. Mucociliary transport was accelerated by the application of 10^?6 M 5-HT. Mucus secretion was also stimulated significantly by 5-HT (30 mg/kg). 5-HT in the mucosa was detected by a chromatographic technique when a large amount of 5-HT precursor, 5-hydroxytryptophan (5-HTP), was given previously. Phenylhydrazine was used as MAO inhibitor. When phenylhydrazine (20 mg/kg) was given before 5-HTP, 5-HT was markedly concentrated in the mucosa. Radioactive 5-HT was also detected in the mucosa after incubation with [¹⁴C]5-HTP. One hour after systemic administration of [³H]5-HTP, a large number of silver grains appeared in the autoradiograms of some epithelial cells. These results suggest the possibility that epithelial cells with the ability to synthesize 5-HT from 5-HTP exist in ciliated epithelium. A possible functional relationship is proposed between the regulation of mucociliary transport with mucus secretion and 5-HT-containing cells.