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Anabolic response of some tissues to diabetes
BlOCHEMlCAL
MEDICINE
33. 271-278 (1985)
Abstracts to Additional Papers Presented at the Symposium Honoring Dr. Samuel P. Bessman University of Southern California School of Medicine, Los Angeles, California. April 18-19. 1985 Dissociation of Aortic Tissue Renin and the Plasma Levels of Active and Inactive Renin in the One- and Two-Kidney Goldblatt Hypertensive Rat. J. D. BARRETT, P. EGGENA, AND M. P. SAMBHI. Veterans Administration Medical Center, Sepulveda. California 91343. Renin-like enzymes of aortic tissue (ATR) increase in renovascular hypertension (RVHT). In the one clip two-kidney model, the increase of ATR may be related to the increased levels of active plasma renin (APR). Little is known regarding the possible contribution of inactive plasma renin (IPR) to ATR. In the present study, we followed APR, IPR (trypsin activation), and ATR in the one- (IK) and two-kidney (2K) single clip RVHT rat for 12 weeks. Systolic blood pressure (BP) increased significantly from a control value of 109 * 5 to 157 t 5 (IK) and 145 i 4 (2K). In the IK group, ATR increased significantly from 0.4 2 0.2 to 12.6 2 7.6 with no change in APR or IPR. APR and IPR, however. did change in the 2K group (n = 6):
APR (ng AI/ml/hr) IPR (ng AI/ml/hr) ATR (ng AI/g/hr)
Control
I week
4 weeks
12 weeks
3.4 2 1.8 4.7 2 2.6 0.4 2 0.2
2.7 rt 0.8 18.2 ? 4.1* 1.6 k 0.6*
6.7 2 0.9” 16.2 k 5.2” 11.3 2 3.4*
8.2 -+ 1.4* 5.0 k 1.5 18.3 5 7.5*
*P < 0.05 as compared to control No correlation was observed between APR and IPR or between APR or IPR and ATR when all time periods were combined. In both models, ATR increased concomitant with BP. Since ATR increased in both models, yet APR and IPR increased only in the 2K group. we conclude that elevated APR or IPR are not prerequisites for high ATR. It is unlikely that elevated pressure alone increases ATR since ATR is depressed in both DOCA-salt HT and in SHR. In RVHT the increase of ATR may be due to the ischemic kidney. Elevation of ATR in the 2K group to levels higher than observed in 1K animals may be due to the higher APR. However. if IPR is activated in vii10 by endothelial cells of aortic tissue as has been demonstrated in vitro, elevated ATR may result from increased IPR in the 2K group. In taivo activation of IPR may explain the progressive fall of IPR in the 2K group and the higher levels of ATR and APR. Anabolic
Response of Some Tissues to Diabetes. F. BELFIORE, A. M. RABUAZZO. S. IANNELLO. AND D. VASTA. I” Istituto Patologia Medica. Chair of Pathophysiology of Metabolism, University of Catania Medical School, Ospedale Garibaldi, 95123 Catania, Italy.
R.
CAMPIONE.
In contrast to liver, adipose tissue, and muscle, in which the diabetic state is associated with a “catabolic response,” some tissues, typically the kidney and perhaps the intestinal mucosa and some vascular cell types, show an “anabolic response” to diabetes, with enhanced activity of the anabolic pathways and diminished activity of the catabolic ones. The kidney of alloxan- or streptozotocindiabetic rats is hypertrophied, and shows enrichment in intracellular glycogen and abundant accumulation of glycoprotein material at the basement membrane level. Accordingly, protein synthesis and the 271 ooO6-2944185 $3.00 Copyright % 1985 by Academic Press, Inc. All rghts of reproduction in any form reserved.
272
ABSTRACTS
FROM SYMPOSIUM
HONORING
DR. BESSMAN
enzymes ofglucose utilization as well as those engaged in UDP sugar formation or in the hydi-oxylation and glycosylation processes (required for glycoprotein synthesis) show increased activity in the diabetic kidney. while the catabolic, lysosomal enzymes tcathepsin D and several glycosidasezt are depressed. We observed a reduction of 24% in the activity of cathepsin D and 23% in that of’ galactosidase in the kidney of streptozotocin-diabetic mice. as opposed to an increase of 1!cI’,:, and of 32%, respectively, found in liver. It is not known which factor(s) may be responsible for \uch an anabolic response of some tissues to diabetes. but persistent hyperglycemia and/or some hormonal abnormalities may be involved. The above data refer to changes in tissue enzyme content caused by induction-repression mechanisms; but rapid (activation-inhibition) effects may also occur. Wr observed that preincubation of slices of mouse kidney cortex for IO mitt with 20.8 mmole/liter glucose resulted in an 80% activation of phosphofructokinase. as assayed in the tissue homogenate at physiological (50 pmole/liter) concentration of the substrate fructose-6-P. suggesting that hyperglycemia may he responsible for some of the metabolic changes occurring in the diabetic kidney. Correlution
of Platelet
Size and Platelet
J. 1). BESSMA>~R. M. DE\\r\. 1.. (‘. How ‘\KLI. and Biochemistry. University of Texas Medical
Sur~~iLul.
F. H. GARDNER, Departments of Medicine Branch. Galveston. Texas. AND
Platelet size (mean platelet volume. MPV) often has been considered a reflection of platelet
Dru,g
Metaboli.snl
und C’onjugution:
Exfec,t
qf’ Mugttc.\irrttr
A \.trhbrlit>,.
WI
K.
BIULAC
L
R. C. BROWN, Department of Pharmacology and Nutrition, University of Southern C’alifornia School of Medicine. 2025 Zonal Avenue. Los Angeles. California 90033. AND
Isolated parenchymal cells were prepared from rat liver using collagenasc perfusion. and pm tlicd by a self-generating percoll gradient. To evaluate drug metabolism and conjugation, I’-nitroanisole (pNA) was used. pNA is O-demethylated to p-nitrophenol (pNPl by the cytochrome P-450 dependent mixed function oxidase (MFOl and in turn is conjugated by sulfotransferase (ST) to pNP-sulfate (pNPS) and by glucuronyl transferase (GT) to pNP-glucuronide lpNPG1. In control (magnesium sufficient) cells the formation of pNP increased relative to the pNA concentration. At the loue~ concentrations of pNA. sulfalion of pNP was the primary conjugate, while at higher pNA concentration\ glucuronidation increased. The amount of free (nonconjugated) pNP also increased in proportion ti) the amount of pNA metabolized. Hepatocytes prepared from Mg-depleted animal\ metabolized Jr\\ pNA to pNP, suggesting loss of MFO activity. Although lower in concentration. the metaboiite pattern for both pNP and PNP-sulfate (pNPSl remained similar IO that observed in the cnntrol cells However, glucuronidation was greatly diminished. The loss of both MFO and GT activities suggest
MEDICINE
33. 271-278 (1985)
Abstracts to Additional Papers Presented at the Symposium Honoring Dr. Samuel P. Bessman University of Southern California School of Medicine, Los Angeles, California. April 18-19. 1985 Dissociation of Aortic Tissue Renin and the Plasma Levels of Active and Inactive Renin in the One- and Two-Kidney Goldblatt Hypertensive Rat. J. D. BARRETT, P. EGGENA, AND M. P. SAMBHI. Veterans Administration Medical Center, Sepulveda. California 91343. Renin-like enzymes of aortic tissue (ATR) increase in renovascular hypertension (RVHT). In the one clip two-kidney model, the increase of ATR may be related to the increased levels of active plasma renin (APR). Little is known regarding the possible contribution of inactive plasma renin (IPR) to ATR. In the present study, we followed APR, IPR (trypsin activation), and ATR in the one- (IK) and two-kidney (2K) single clip RVHT rat for 12 weeks. Systolic blood pressure (BP) increased significantly from a control value of 109 * 5 to 157 t 5 (IK) and 145 i 4 (2K). In the IK group, ATR increased significantly from 0.4 2 0.2 to 12.6 2 7.6 with no change in APR or IPR. APR and IPR, however. did change in the 2K group (n = 6):
APR (ng AI/ml/hr) IPR (ng AI/ml/hr) ATR (ng AI/g/hr)
Control
I week
4 weeks
12 weeks
3.4 2 1.8 4.7 2 2.6 0.4 2 0.2
2.7 rt 0.8 18.2 ? 4.1* 1.6 k 0.6*
6.7 2 0.9” 16.2 k 5.2” 11.3 2 3.4*
8.2 -+ 1.4* 5.0 k 1.5 18.3 5 7.5*
*P < 0.05 as compared to control No correlation was observed between APR and IPR or between APR or IPR and ATR when all time periods were combined. In both models, ATR increased concomitant with BP. Since ATR increased in both models, yet APR and IPR increased only in the 2K group. we conclude that elevated APR or IPR are not prerequisites for high ATR. It is unlikely that elevated pressure alone increases ATR since ATR is depressed in both DOCA-salt HT and in SHR. In RVHT the increase of ATR may be due to the ischemic kidney. Elevation of ATR in the 2K group to levels higher than observed in 1K animals may be due to the higher APR. However. if IPR is activated in vii10 by endothelial cells of aortic tissue as has been demonstrated in vitro, elevated ATR may result from increased IPR in the 2K group. In taivo activation of IPR may explain the progressive fall of IPR in the 2K group and the higher levels of ATR and APR. Anabolic
Response of Some Tissues to Diabetes. F. BELFIORE, A. M. RABUAZZO. S. IANNELLO. AND D. VASTA. I” Istituto Patologia Medica. Chair of Pathophysiology of Metabolism, University of Catania Medical School, Ospedale Garibaldi, 95123 Catania, Italy.
R.
CAMPIONE.
In contrast to liver, adipose tissue, and muscle, in which the diabetic state is associated with a “catabolic response,” some tissues, typically the kidney and perhaps the intestinal mucosa and some vascular cell types, show an “anabolic response” to diabetes, with enhanced activity of the anabolic pathways and diminished activity of the catabolic ones. The kidney of alloxan- or streptozotocindiabetic rats is hypertrophied, and shows enrichment in intracellular glycogen and abundant accumulation of glycoprotein material at the basement membrane level. Accordingly, protein synthesis and the 271 ooO6-2944185 $3.00 Copyright % 1985 by Academic Press, Inc. All rghts of reproduction in any form reserved.
272
ABSTRACTS
FROM SYMPOSIUM
HONORING
DR. BESSMAN
enzymes ofglucose utilization as well as those engaged in UDP sugar formation or in the hydi-oxylation and glycosylation processes (required for glycoprotein synthesis) show increased activity in the diabetic kidney. while the catabolic, lysosomal enzymes tcathepsin D and several glycosidasezt are depressed. We observed a reduction of 24% in the activity of cathepsin D and 23% in that of’ galactosidase in the kidney of streptozotocin-diabetic mice. as opposed to an increase of 1!cI’,:, and of 32%, respectively, found in liver. It is not known which factor(s) may be responsible for \uch an anabolic response of some tissues to diabetes. but persistent hyperglycemia and/or some hormonal abnormalities may be involved. The above data refer to changes in tissue enzyme content caused by induction-repression mechanisms; but rapid (activation-inhibition) effects may also occur. Wr observed that preincubation of slices of mouse kidney cortex for IO mitt with 20.8 mmole/liter glucose resulted in an 80% activation of phosphofructokinase. as assayed in the tissue homogenate at physiological (50 pmole/liter) concentration of the substrate fructose-6-P. suggesting that hyperglycemia may he responsible for some of the metabolic changes occurring in the diabetic kidney. Correlution
of Platelet
Size and Platelet
J. 1). BESSMA>~R. M. DE\\r\. 1.. (‘. How ‘\KLI. and Biochemistry. University of Texas Medical
Sur~~iLul.
F. H. GARDNER, Departments of Medicine Branch. Galveston. Texas. AND
Platelet size (mean platelet volume. MPV) often has been considered a reflection of platelet
Dru,g
Metaboli.snl
und C’onjugution:
Exfec,t
qf’ Mugttc.\irrttr
A \.trhbrlit>,.
WI
K.
BIULAC
L
R. C. BROWN, Department of Pharmacology and Nutrition, University of Southern C’alifornia School of Medicine. 2025 Zonal Avenue. Los Angeles. California 90033. AND
Isolated parenchymal cells were prepared from rat liver using collagenasc perfusion. and pm tlicd by a self-generating percoll gradient. To evaluate drug metabolism and conjugation, I’-nitroanisole (pNA) was used. pNA is O-demethylated to p-nitrophenol (pNPl by the cytochrome P-450 dependent mixed function oxidase (MFOl and in turn is conjugated by sulfotransferase (ST) to pNP-sulfate (pNPS) and by glucuronyl transferase (GT) to pNP-glucuronide lpNPG1. In control (magnesium sufficient) cells the formation of pNP increased relative to the pNA concentration. At the loue~ concentrations of pNA. sulfalion of pNP was the primary conjugate, while at higher pNA concentration\ glucuronidation increased. The amount of free (nonconjugated) pNP also increased in proportion ti) the amount of pNA metabolized. Hepatocytes prepared from Mg-depleted animal\ metabolized Jr\\ pNA to pNP, suggesting loss of MFO activity. Although lower in concentration. the metaboiite pattern for both pNP and PNP-sulfate (pNPSl remained similar IO that observed in the cnntrol cells However, glucuronidation was greatly diminished. The loss of both MFO and GT activities suggest