Comparison of subcutaneous and intraportal insulin administrations on adenylate energy charge of the liver in diabetic rats

Effects of subcutaneous and intraportal administrations of insulin on adenine nucleotide metabolism of the liver and oxidative phosphorylation of the isolated mitochondria were investigated in alloxan-diabetic rats. The diabetic rats were classified into two groups according to the severity of impaired insulin response to oral glucose: diabetic rats with only minor impairment of insulin response and those with severely defective response. The energy charge levels (ATP + 1/2ADP)/(ATP + ADP + AMP) of the liver both groups were not significantly different from those of controls. In the first group, the oxidative phosphorylation of liver mitochondria was within normal limits and was enhanced significantly by subcutaneous administration 4 U. of insulin (p less than 0.005). In the secong group, the mitochondrial oxidative and phosphorylative activities were inhibited severely and did not recover even with subcutaneous administration of 20 U. of insulin. Intraportal administration of insulin doses (4 to 8 U.) insufficient for normalization of hyperglycemia produced a decrease in the energy charge of the liver to a considerably lower level than normal (p less than 0.01), whereas larger doses (20 U.) of insulin raised the energy charge to normal levels, with a concomitant recovery of mitochondrial oxidative phosphorylation. It is suggested that subcutaneous administration of insulin is effective for hepatic energy metabolism only if insulin response to glucose loading is still present but that only intraportal administration of insulin can exert a beneficial effect in diabetic rats without insulin response.

Adaptive increase of respiratory enzymes in the mitochondria from cirrhotic livers of patients and rats, and its relationship to glucose tolerance

Oxidative phosphorylation and respiratory enzyme concentrations of liver mitochondria and glucose tolerance were studied in 12 cirrhotic patients and CCl4-induced cirrhotic rats. The cirrhotic patients with normal or higher concentrations of cytochrome a(+a3) showed parabolic glucose tolerance test (GTT) patterns having return of blood glucose level somewhat toward normal within two hours and tolerated major operations well, while three patients with cytochrome a(+a3) concentrations less than 60 per cent of normal (0.81 +/- 0.02 (mean +/- SEM) X 10(-10) moles/mg protein) could not tolerate even minor operations. In CCl4-induced cirrhotic rats, cytochrome a(+a3) concentrations varied from 1.5 to 3.0 X 10(-10) moles/mg protein as compared with 1.8 +/- 0.1 of controls. In mitochondria with normal or higher concentrations of cytochrome a(+a3), the oxidative and phosphorylative activities per unit of cytochrome a(+a3) were negatively correlated with cytochrome a(+a3) concentrations. These rats tolerated partial hepatectomy well. However, in cirrhotic rats with subnormal cytochrome a(+a3) concentrations there was a high mortality following hepatectomy. The former showed parabolic GTT patterns, while the latter showed nonparabolic GTT patterns.

Changes in mitochondrial phosphorylative activity and adenylate energy charge of regenerating rabbit liver

The changes in the cellular concentrations of ATP, ADP, and AMP and in oxidative phosphorylation of mitochondria were investigated in the remaining liver of partially hepatectomized rabbits. The energy charge (defined as half of the average number of anhydride-bonded phosphate groups per adenosine moiety) of the liver remnant decreased from 0.866 to 0.767 (p less than 0.01) within 24 hr after hepatectomy, and then increased to a substantially higher level than normal within 7 days. On the other hand, the mitochondrial phosphyorylative activity increased rapidly to 170 per cent of the control within 12 hr and then retruned to normal within 7 days. The mitochondrial phosphorylative activity was inversely correlated with energy charge of the liver remnant (r = -0.75, p less less than 0.01). The maximal enhancement of mitochondrial phosphorylative activity was found in mitochondria obtained from the liver remnant with the lowest level of energy charge, suggesting a response of mitochondria in vivo involving enhanced biosynthetic ATP-utilizing reactions at an early stage of the regenerating process. The enhancement of phosphorylative activity was accompanied by a rise in the respiratory control ratio, P/O ratio and state 3 respiration. The adenylate kinase [EC 2.7.4.3] activity in the liver remnant increased to more than 160% of the control within 2 days after partial hepatectomy, while the pyruvate kinase [EC 2.7.1.40] activity decreased remarkably. However, the changes in the two enzyme activities did not correlate with those of mitochondrial phosphorylative activity or the energy charge of the liver remnant.

Effect of insulin on mitochondrial oxidative phosphorylation and energy charge of the perfused guinea pig liver

The effect of insulin was investigated in the isolated guinea pig liver perfused with Krebs-Ringer bicarbonate buffer containing red blood cells and albumin. In the mitochondria isolated from livers perfused with 10 units of insulin per hour, the phosphorylative activity with glutamate as a substrate increased to about 160 per cent of control 60 minutes after the beginning of perfusion (p less than 0.01). Such an enhanced phosphorylative activity was accompanied by increases in the respiratory control ratio, state 3 respiration, and P/O ratio. On the other hand, in the liver perfused with insulin, the levels of the energy charge and adenine nucleotide quotient increased to a significant degree as compared to the liver without insulin (p less than 0.01 and p less than 0.05, respectively). It is suggested that insulin plays an important role as a portal factor in regulating mitochondrial oxidative phosphorylation and the levels of the phosphorylated adenine nucleotides.

Changes in adenylate energy charge of the liver after an oral glucose load

Changes in the adenine nucleotide metabolism after an oral glucose load were studied in the liver of normal and alloxan-diabetic rats. Changes in the energy charge were positively correlated with those in the blood glucose and plasma immunoreactive insulin levels. One hour after an oral glucose load when the plasma immunoreactive insulin levels increased maximally, the energy charge increased maximally from 0.846 to 0.867 (P less than 0.001). The increase in the energy charge was accompanied by a concomitant decrease in the ADP levels (P less than 0.05). The respiratory control ration, state 3 respiration per unit of cytochrome a (+a3), and DNP-induced ATPase activity per unit of cytochrome a (+a3) increased significantly. The adenylate kinase and pyruvate kinase activities in the liver remained unchanged. On the other hand, the energy charge in the liver of alloxan-diabetic rats did not increase significantly after an oral glucose load. It was suggested that an increase in the energy charge of the liver is attributable to the more rapid flux of intermediary metabolism in the enhanced ADP-phosphorylating reactions by mitochondria, owing to an elevated level of insulin available to the hepatic cells.

A direct method for the estimation of ornithine carbamoyltransferase activity in serum

Ornithine carbamoyltransferase (EC 2.1.3.3) activity was estimated by determining the amount of citrulline produced. The citrulline was colorimetrically measured by using a diacetylmonoxime-thiosemicarbazide reaction without deproteinization. The color complex which had the maximum absorbance at 515 nm was stable at room temperature in daylight for at least several hours. The proposed method was superior to other methods already reported in sensitivity, stability and simplicity.

[Microbiological study of alcohol-impregnated cotton used for skin antisepsis before injections]

Estudo preliminar sobre as condições microbiológicas do algodão embebido em álcool, preparado para a antissepsia da pele antes da injeção. O trabalho foi realizado utilizando-se de dois grupos de vinte frascos contendo algodão embebido em álcool (Grupo I e II), colhen-do-se amostras, de cada frasco no momento do preparo e cada 24 horas, durante 4 dias. No Grupo I, em que o algodão foi retirado diretamente com a mão, a condição asséptica do material foi mantida por 24 horas de uso (1 dia). A partir do segundo dia foi observada contaminação por germes Gram positivos e Gram negativos. No Grupo II, em que as bolas de algodão foram retiradas com pinça esterilizada, a contaminação se manifestou tardiamente, no 4.° dia (96 horas) e em apenas duas amostras (frascos).

Clinical application of cytochrome a(plus a3) assay of mitochondria from liver specimens: an aid in determining metabolic tolerance of liver remnant for hepatic resection

Measurement of cytochrome a(+a(3)) contents in liver mitochondria was made on 52 biopsy specimens of patients with liver tumor. Patients having higher cytochrome a(+a(3)) contents in mitochondria from remaining liver than those of normal human liver mitochondria could survive well major liver resections whether or not associated with liver cirrhosis. However, patients with cytochrome a(+a(3)) contents less than 0.5 x 10(-10) moles per mg protein showed a high rate of postoperative complication (80%) and death (40%) in spite of minor operation. In routinely used liver function tests such as serum albumin, A/G ratio, SGOT, total bilirubin, prothrombin time, BSP and TTT, there were no significant differences between patients with cytochrome a(+a(3)) contents more than 0.5 x 10(-10) moles per mg protein and those less than 0.5. The results indicate that routine laboratory studies do not have much diagnostic value in estimation of a marked decrease of mitochondrial cytochrome a(+a(3)) contents. It is suggested that the measurements of cytochrome a(+a(3)) of the remnant liver should be done prior to a contemplated major resection.