Naci M. Bor

Changes of reduced glutathion, glutathion reductase, and glutathione peroxidase after radiation in guinea pigs☆

In this series of experiments the protective action of reduced glutathion due to ionizing radiation has been studied. In the experimental group 18 guinea pigs were exposed to successive radiations of 150 rad 3 or 4 days apart. Total dose given amounted to 750 rad which is the LD50 for guinea pigs. Blood samples were taken 30 min after each exposure. The control series were sham radiated but otherwise treated identically. The cells of the removed blood samples were separated by centrifugation and were subjected to the reduced glutathion stability test. GSSGR, GPer, and LDH enzyme activities were also measured of which the latter served as a marked enzyme. It was found that LDH did not show any alteration after radiation. The reduced glutathion stability test showed a consistent but minor reduction (P greater than 0.05), in the experimental group. GSSGR enzyme activity on the other hand was reduced significantly (from 176.48 +/- 11.32 to 41.34 +/- 1.17 IU/ml of packed erythrocytes, P less than 0.001) in the same group. GPer activity showed a consistent but minor elevation during the early phase of the experimental group. It was later increased significantly beginning after 600 rad total radiation on the fourth session (P less than 0.050).

Measurement of pancreatic blood flow in dog by133Xe clearance technique

SummaryThe water/gas, plasma/gas, erythrocyte/gas and pancreas/gas partition coefficients of133Xe were measured at 37° C using dog tissues. The pancreas/blood partition coefficients were calculated from these figures and plotted as a function of hematocrit. The133Xe pancreas/blood partition coefficient in the normal range was 1.2 ml/g.Pancreatic blood flow was determined in each case by injecting the tracer into the pancreaticoduodenal artery (mean 106.8±30.4 ml/100 g/min). Pancreatic blood flows were also determined by injecting the tracer into the tissue of head, body and the tail of pancreas. The means of the results were 62.4±22.2, 85.7±35.6 and 67.1±26.4 ml/100 g/min respectively. The mean pancreatic blood flow obtained by intra-arterial injection was significantly different (P<0.05) from the results obtained by injecting133Xe into the head or tail, but was not statistically different from that of the body of pancreas. The results of the head, body and tail of pancreas were not significantly different from each other (P>0.05).

The effects of epinephrine on guinea pig placental glycogen metabolism and on cellular cyclic AMP.

Abstract In order to study the effects of epinephrine on placental glycogen metabolism and on its cellular cAMP experiments were carried out on three groups of pregnant guinea pigs. Under the effect of epinephrine plasma cAMP concentration rose sharply within 1 min, reached a maximum at 5 min, and returned to control levels by 10 min. Blood glucose began rising in 5 min, arrived at a maximum in 10 min, and remained elevated thereafter. Placental cellular cAMP reached a maximum in 1 min and returned to control levels within 15 min. Glycogen phosphorylase was most active at 10 min after hormone administration while glycogen synthetase activity was significantly reduced at 5 min. Glycogen content of the placenta was reduced constantly, reaching a minimum at 15 min. The results of this investigation support the hypothesis that glycogenolysis produced by epinephrine in placenta is mediated by cellular cAMP.

Calculation of net insulin secretion and pancreatic blood flow

SummaryUsing133Xe washout technique pancreas blood flow has been calculated. Injected the radio-tracer into a small branch of the pancreatico-duoodenal artery pancreatic blood flow rate was found 106.69±9.95 ml/100 g/min. Insulin concentrations of the peripheral and pancreatic veins have been determined and net insulin secretion have been calculated. Under our experimental conditions it was found 8.97±1.91 mU/100 g/min. The same parameters were calculated after injecting the nuclide into the head, corpus and tail of the pancreas separately and the results were compared to that of intra-arterial injection.This approach is proposed as a quantitative method of evaluating β cell function under various physiological and pathological conditions.

Hepatic blood flow during rapid intravenous glucose tolerance test

SummaryTwenty-nine dogs anesthetized with Na-pentobarbital were laparatomized and liver blood flow was measured by133Xe clearance method. Fifteen dogs of the experimental group were subjected to rapid i.v. glucose tolerance test whereas 14 animals of the control group were treated identically except for infusion of glucose. It was found that the arterial and the portal venous blood glucose rose significantly during the glucose tolerance test. Liver blood flow in the experimental group was 123.8 ml/100g L/min after operative procedures. It reached 171.9 ml/100g L/min at 10 min after infusion of glucose (P<0.01). At 20, 30, and 40 min of the test it was 145.4 (P<0.05), 143.4 (P<0.01), 135.1 (P>0.05) mg/100g L/min, respectively. Liver blood flow did not change significantly during the observation period in the control series. It is concluded that glucose loading may produce some metabolic effects secondary to rising liver blood flow in addition to changes induced by its rising concentration.

Pancreatic blood flow in hemorrhagic shock

Pancreatic blood flow rates were determined using a133Xe washout technique in a total of 40 dogs, 14 of which were used as a control group and the remaining 26 as the experimental group. The initial pancreatic blood flow rates of control group and of the experimental group were 85.1±10.1 ml/100g/min of pancreas/min and 81.1±5.4 ml/100g/min respectively. These values were not significantly different from each other (P>0.05). In the control group the blood flow was determined 3 times at 30 min intervals. These mean values were 73.0±9.4, 74.6±8.7, and 79.4 ±10.4 ml/100g/min respectively (P>0.05). The dogs in the experimental group were bled and the peripheral arterial blood pressure was reduced stepwise to 80, 50, and 30 mm Hg. At each level a 30 min of stabilization period the pancreatic blood flow rates were 49.8±3.7, 29.3±2.3 and 20.2±2.3 ml/100g/min respectively. These mean values were very significantly reduced compared to those of the control group, at 30 min (P<0.02), at 60 and 90 min (P>0.001). They were also very significantly different from their own initial values (P<0.001). the metabolic consequences of this reduction in pancreatic blood flow are discussed.

Phagocytosis by macrophages in zinc-deficient rats

Phagocytosis by polymorphonuclear cells has been found to be significantly reduced in zinc-deficient patients and this finding was confirmed in animal experiments. In order to find out whether phagocytosis by macrophages is similarly altered, experiments were conducted in three groups of 18 rats. Control, zinc-deficient and pair-fed rats were given 99mTc nanocolloid intravenously. In ten other experiments (5 experimental and 5 control rats) 99mTc-sulfur colloid was injected intravenously. The biodistribution was determined by a well-type gamma counter and the results were evaluated statistically. The greatest amount of radioactivity was taken up by the liver, followed by the spleen, lung and kidney. In both series of experiments however the zinc-deficient animals appeared to take up a greater amount of the radiotracer (P less than 0.05).

Changes of bile lipid composition induced by methylprednisolone

Experiments were carried out on three groups of male guinea pigs to study the influence of methylprednisolone on the bile lipid composition. The cholesterol, phospholipid, and bile acids concentrations of the gallbladder bile in the control series were not significantly different from those of Group II, receiving SF for 45 days. In the methylprednisolone group, however, the absolute and relative molar concentrations of cholesterol increased while those of bile acids decreased compared to the former groups. Phospholipids on the other hand revealed only a relative increase. The observations indicate that use of methyl prednisolone for 45 days increases the lithogenicity of the bile in guinea pigs.

Liver blood flow rate and glucose metabolism in hemorrhagic hypotension and shock.

Liver blood flow was measured in dogs using 133Xe clearance technique under control conditions and during various stages of hypotension and of hemorrhagic shock. Initial liver mean blood flow rate in all dogs combined are 101.9 +/- 11.5 ml/100 gm liver/min and was not significantly altered in the control group. Liver blood flow rate was reduced in the experimental group during hemorrhagic hypotension and shock and was correlated with the severity of the disease. Peripheral vasodilatation was observed in one subgroup of experimental animals while severe vasoconstriction was found in another subgroup. Glucose concentrations in the hepatic vein were significantly above that of arterial and portal venous blood; all experimental animals were hyperglycemic. The outflow of glucose from the liver was increased during shock in ten animals. It was, however, reduced in 17 animals.

Net insulin secretion and IRI response to 1 mg glucose during OGTT.

SummaryDogs in postabsorbtive state were anesthetized with IV nembutal. Their femoral arteries were catheterized, and the abdomina were entered via a midline incision. A small branch of the pancreatic artery and a corresponding small vein were catheterized.133Xe was injected through the artery, and the pancreatic blood flow rate (PBFR) was determined. Net insulin secretion was calculated using the insulin concentration of pancreatic vein-artery difference and pancreatic plasma flow rate (PPFR). After control studies an oral glucose tolerance test (2 g/kg body wt.) was performed. Under control studies the mean value of net insulin secretion was 3,753.2±699.1 µU/100 g P/min and the maximum values were 10,610.2±3,658.7 and 11,108.0±2,852.6 µU/100 g P/min at 20 and 60 min after glucose loading, respectively (P < 0.05). Insulin response per mg of glucose was 83.2±12.2 µU under control conditions. Twenty minutes after glucose loading this figure rose to 173.4±41.7 µU/mg glucose and at 60 min 207.9±49.2 µU/mg glucose.