- Effect of Heat Shock on the Vascular Reactivity in Diabetic Rat Aorta.
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Seong Mo Koo, Soon Hee Lee, Jung Hun Han, Gi Young Jeong, In Kyum Kim, Jung Guk Kim, Sung Woo Ha, Bo Wan Kim
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Korean Diabetes J. 2001;25(5):343-353. Published online October 1, 2001
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 Abstract
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- BACKGROUND
Heat shock has been known to change cellular response to noxious stimuli by inducing heat shock proteins (HSP). HSP are expressed in many tissues, and increased expression of some HSP enhances the survival of cells exposed to oxidative stress. Recently, Some HSP are known to associate with vascular reactivity. Under diabetic conditions, there is abnormal vascular reactivity to relaxing or contracting factors. Abnormal vascular response to some stimuli is an important role in the development of diabetic complications. However, the effects of heat shock on the vascular reactivity in diabetic condition is unclear. Therefore, we investigated effects of heat shock on the vascular reactivity in isolated aorta of streptozotocin-induced diabetic rats. METHODS: After mounced in organ bath, aortic ring preparations were exposed to 42 for 45 minutes followed by being subjected to contraction and relaxation in 4 hours. Tissues were frozen for measurement of HSP 70 and phosphorylation of myosin light chain after functional study. RESULTS: Heat shock not only increased expression of HSP70 in rat aorta but also augmented contraction to KCl and phenylephrine in the aorta of control and diabetic rats (p<0.05). Relaxation responses to acetylcholine (ACh) were not changed in the aorta of control rats with and without heat shock for 45 minutes. However, heat shock for 45 minutes decreased relaxative responses to ACh in the aorta of diabetic rats compared to those in the aorta of control rats. CONCLUSION: This result suggests that heat shock increases vascular contractility in the aorta of diabetic and control rats through the induction of HSP70 while heat shock seems to decrease relaxative response in the aorta of diabetic ratscompared to control rats (p<0.05). Whether heat shock impaired relaxative response in the aorta of diabetic rats deserves additional studies.
- Effect of Transforming Growth Factor-B1 and Platelet Derived Growth Factor on Synthesis and Gene Expression of Collagen and Non-Collagen Protein in Aortic Smooth Muscle Cells Cultured in Different Concentrations of Insulin and Glucose.
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Kun Young Sohn, In San Kim, Bo Wan Kim, Jung Guk Kim, Sung Woo Ha, Jick Hwa Nam, Seong Mo Koo, Rang Woon Park, Sam Kweon
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Korean Diabetes J. 1999;23(4):518-529. Published online January 1, 2001
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Abstract
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The mechanism for accelerated atberosclerosis in diabetes mellitus is unclear although diabetes mellitus is associated with substantial increase in prevalence of atherosclerotic disease. Extracellular matrix formation by vascular smooth muscle cells has been accepted as playing important roles during development of atherosclerosis. High glucose condition has been reported to increase the synthesis of extracellular matrix such as collagen and fibronectin in cultured mesangial cells. Insulin and some cytokines such as TGF-B and PGF have also been reported to stimulate the synthesis of collagen in mesangial cells. So we studied the effect of high glucose, insulin, TGF-Band PDGF on vascular smooth muscle cells. METHODS: To determine the effect of bigh glucose condition on collagen synthesis in vascular smooth muscle cells, cells were grown in the culture medium containing either normal (5.5 mM) or high (25 mM) glucose. And we used several concentrations of TGF-B1PDGF-BB and insulin in order to determine the synergistic effects of collagen synthesis and type I collagen mRNA expression. RESULTS: We observed that cells cultured in high glucose media synthesized more collagen and increased expression of type I collagen mRNA as compared to normoglycemic media. The amount of synthesized collagen and type I collagen mRNA expression increased proportionally to the increase in insulin concentration. There was no relationship of TGF-B1or PDGF-BB with the expression of type I collagen mRNA but these cytokines stimulated the synthesis of collagen and noncollagen protein. There was no synergistic effect of col)agen synthesis and type 1collagen mRNA expression by high glucose, insulin, and cytokines. CONCLUSION: These results suggest that TGF-Band PDGF may not influence type I collagen mRNA expression under hyperglycemia or hyperinsulinemia in vascular smooth muscle cells. Further studies about the other types of collagen expressions such as type IV, and V are needed because TGF-Band PDGF stimulated the synthesis of collagen and noncollagen protein.
- Association Between QTc Dispersion and Cardiovascular Autonomic Dysfuction in Non-insulin Dependent Dabetes Mellitus.
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Jung Guk Kim, Hun Sik Park, Jick Hwa Nam, Byoung Ho Sin, Seong Mo Koo, Sung Woo Ha, Bo Wan Kim
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Korean Diabetes J. 1998;22(2):173-181. Published online January 1, 2001
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Abstract
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Diabetic patients with autonomic dysfunction have worse prognosis, including an increased incidence, of sudden death, than those without autonomic dysfunction. This event may be due to sympathetic imbalance causing disturbances of ventricular repolarization. QT dispersion have recently been demonstrated to reflect dispersion of ventricular refractoriness and is a marker of arrhythmogenic potential. METHODS: Sixty diabetic patients and 31 normal subjects were studied. All patients had clinical test for cardiovascular autonomic dysfunction by Ewings method and defined as normal, early involved, definitely involved, severely involved and atypical group for 5 validated tests. Resting standard 12-lead electrocardiograms were recorded for measurement of QT dispersion, defined as the difference of longest QT interval and shortest QT interval, and corrected for heart rate using Bazetts formula. RESULTS: Twenty-seven dIiabetic patient were abnormal in cardiovascular autonomic function tests. In these patients corrected QT dispersion (QTc) were significantly longer compared to that 33 patients without autonomic dysfunction(47.4+14.7 vs 22.6+ 8.1msec p<0.001). And also there was significant difference of QTc dispersion between normal subject and diabetic patients with autonomic neuropathy group(20.5+9.2 vs 47.4+14.7msec p<0.001). But there was no difference between normal control and diabetic patients without autonomic neuropathy group. And QTc dispersion was not related to the presence ot nephropathy, retinopathy or peripheral polyneuropathy. We also found that there was no relationship between the severity of autonomic neuropathy and degree of Q7c dispersion. CONCLUSION: We concluded that QTc dispersion may be a good method for evaluation of cardiovascular autonomic neuropathy and increased QTc dispersion may be one of the markers of arrhythmia in diabetic patients with autonomic neuropathy.
- Relationship between Peripheral Neuropathy and Cardiovascular Autonomic Neuropathy in Non-Insulin Dependent Diabetics.
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Sung Woo Ha, Hyun Jeong Lee, Jeung Hun Han, Sang Won Jung, Jick Hwa Nam, Byoung Ho Sin, Seong Mo Koo, Jung Guk Kim, Sam Kwon, Bo Wan Kim
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Korean Diabetes J. 1997;21(4):476-483. Published online January 1, 2001
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Abstract
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Autonomic neuropathy was detected in some diabetics with symmetric peripheral neuropathy, a common complication of diabetes mellitus that may be associated with considerable morbidity. There has been known to be similarity of pathogenic mechanism in two neuropathies. Then we examined nerve conduction velocity and cardiovascular autonomic function tests. We studied relationship between peripheral and cardiovascular autonomic neuropathy in non-insulin dependent diabetics. METHODS: We studied 166 patients with or witbout peripheral neuropathy who had been diagnosed as non-insulin dependent diabetes mellitus. We examined nerve conduction tests to assess diabetic peripheral neuropathy and classified them into 4 groups aecording to neuropathic symptoms and results of nerve conduction tests. We examined five cardiovascular autonomic function tests by Ewing's methods. RESULTS: 1. The duration of diabetes mellitus was significantly longer in the group of cliabetics with neuropathic symptoms and abnormal findings in the nerve conduction velocity tests than the other groups. The level of blood glucose was significantly higher in the group of diabetics with neuropathic symptoms and findings than the other groups. 2. In the 5 cardiovascular autonomic function tests, heart rate response to deep breathing and Valsalva maneuver had significant differences between the diabetic group with peripheral neuropathy and the other groups. 3. The frequency and severity of autonomic neuropathy were higher in the group with peripheral neuro-pathic symptoms and findings than the other groups without neuropathic syrnptoms and findings. There was an overall significant relationship between sensorirnotor neural function and autonomic function. 4. There was no association between peripheral neuropathy and nephropathy although peripheral neuropathy was related with retinopathy. CONCLUSION: Diabetic peripheral neuropathy accompanies autonomic neuropathy. Then, this result suggests that there is the relationship between peripheral and cardiovascular autonomic neuropathy.
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