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Biomedical subjects

A J Matty

Publications and source records attributed to A J Matty.

At least 37 records · Page 2Linked to original sources
PubMed1976

Immunoreactive insulin in bile and pancreatic juice of rat.

Immunoreactive insulin (IRI) was determined in the bile and pancreatic juice of rats. Recovery studies in which known amounts of insulin were added to samples of these fluids indicated that the IRI values corresponded closely to total recovery. The concentration of IRI in bile and pancreatic juice was greater than the concentration in arterial plasma and less than the concentration in hepatic portal venous plasma adjacent to the liver. Elevation of the circulating IRI concentration in fasting anaesthetized animals by intravenously administered glucose or insulin produced a concomitant increase in the concentration of IRI in bile and pancreatic juice. In fasting conscious animals there was a circadian variation in the concentration of IRI in bile and pancreatic juice similar to the variation of IRI in the circulation. The total amount of IRI in the bile and pancreatic juice of fasting conscious rats during 24 h was in excess of 4 mU/kg body weight. These studies demonstrate that considerable quantities of IRI are transferred from the circulation into the bile and pancreatic juice of rats.

Animals↗
PubMed1975

Acidification in the rat proximal jejunum.

1. Production of hydrogen ions by the rat proximal jejunum was investigated using the everted sac technique. 2. Acidification occurred in the absence of glucose, increasing on addition of glucose to reach a maximal value. An apparent Km of 1-78 mM was derived for the glucose-dependent process. 3. Acidification in the presence of glucose was inhibited by 10 mM-2:4-dinitrophenol, 10 mM phlorrhizin, 10 mM aminophylline and anaerobiosis. 4. Histamine, ethylenediamine tetraacetic acid (EDTA), ouabain and acetazolamide, compounds known to alter acid production in gastric mucosa had no effect on jejunal acidification. 5. Galactose and 3-O-methylglucose failed to increase acidification; in contrast, mannose and fructose did lead to increases, indicating metabolic origin of the hydrogen ions. 6. Serosal and mucosal lactate production were measured and the calculated percentage of hydrogen ions possibly derived from this source was shown to account for only a small proportion of acidification. 7. The greatest increase in acidification with minimal simultaneous production of lactate occurred with ATP which was shown not to enter intestinal tissues. 8. A hypothesis for acidification, that of the break-down at the mucosal surface of ATP from intracellular metabolic sources, is proposed and its relevance to the postulated microclimate is discussed.

Acetazolamide↗
PubMed1975

Uptake of 5-methyltetrahydrofolic acid by the rat jejunum.

1. Everted sacs of rat jejunum were used to study the transport of 5-methyltetrahydrofolic acid at various concentrations and at different pHs. 2. The transport of 5-methyltetrahydrofolic acid appeared to be linear with increasing incubation time at a 5-methyltetrahydrofolic acid concentration of 10(-5) M in the incubating medium. Tissue uptake was much higher than serosal uptake. 3. At 'zero' concentration gradient of 5-methyltetrahydrofolic acid, the transport from mucosal to serosal sides was negligible but tissue uptake was appreciable. 4. Reducing the incubation temperature from 37 to 27 degrees C gave a Q10 value of 1-8. 5. The characteristics of 5-methyltetrahydrofolic acid uptake suggested a non-saturable transport mechanism. 6. Studies were also carried out with isolated mucosal epithelial cells at different incubation times and at different pH values. 7. The over-all results suggest that 5-methyltetrahydrofolic acid transport is most likely a passive diffusion of its zwitterion and also a solvent drag with water flow. 8. The 5-methyltetrahydrofolic acid may be converted to its zwitterion in an acid microclimate at the surface of the intestinal absorbing cell.

Animals↗
PubMed1975

Diurnal variations of food consumption, plasma glucose and plasma insulin concentrations in lean and obese hyperglycaemic mice.

Diurnal variations in food consumption and plasma concentrations of glucose and insulin were determined at 3-hourly intervals in obese hyperglycaemic mice (C57BL/6J ob/ob) and lean mice (C57BL/6J+/+). In lean mice, food consumption and plasma insulin concentrations increased during the light period and were reduced during the dark period, whereas plasma glucose concentrations were maximal at the beginning of the light period and declined to a minimum during the early dark period. In ob/ob mice, the plasma glucose concentration declined temporarily at the beginning of both the light and the dark period and became elevated towards the ends of these periods, but there were no significant diurnal variations of food consumption or plasma insulin concentrations. These observations indicate differences in the diurnal regulation of glucose homeostasis in lean and ob/ob mice.

Animals↗
PubMed1975

Blood glucose and plasma insulin levels during prolonged pentobarbitone anaesthesia in the rat.

Experiments were conducted on 18 hr fasted male Wistar rats at 15 minutes (short-term anaesthetised) and 5 hr (long-term anaesthetised) after the induction of anaesthesia with sodium pentobarbitone, 45 mg/kg body weight intraperitoneally. Long-term anaesthetised animals received supplementary injections of anaesthetic, 10 mg/kg body weight at hourly intervals, or as required to maintain anaesthesia. Normal basal arterial blood glucose and plasma insulin levels were well maintained during 5 hours of anaesthesia. Following an intravenous glucose challenge, plasma insulin levels and insulin-glucose ratios were slightly reduced in the long-term anaesthetised animals, but glucose tolerance was not significantly impaired. The insulin secretory capacity of pancreas pieces isolated from short-term and long-term anaesthetised animals and incubated in vitro in the absence and presence of glucose was not significantly altered. The hypoglycaemic effect of an intravenous injection of insulin was markedly diminished and the rate of elimination of insulin from the circulation was significantly increased in the long-term anaesthetised animals. These observations indicate adjustments of the glucose homeostatic mechanism during prolonged pentobarbitone anaesthesia in fasting rats.

Anesthesia↗
PubMed1974

Absorption of folic acid by everted segments of rat jejunum.

1. Everted rings of rat intestine were used to study the initial uptake rate of folic acid at various concentrations and incubation temperatures in vitro.2. Folic acid was accumulated linearly for periods of at least 30 min.3. The initial uptake rate was found to reach a constant value as the concentration of folic acid in the incubation medium was increased above 5 x 10(-6)M.4. Reducing the temperature of incubation from 37 to 27 degrees C gave small Q(10) values at either end of the concentration range.5. Transfer of folic acid into the serosal compartment of everted sacs was shown to undergo a rate reduction in the same concentration range.6. A mechanism for folic acid transport is suggested in which folic acid is converted to the neutral species at the mucosal surface in an acid microclimate.

Animals↗