Heikki Kainulainen

Exercise enhances vasorelaxation in experimental obesity associated hypertension

OBJECTIVE Regular exercise is recommended for the non-pharmacological treatment of hypertension, but the mechanisms underlying the lowering of blood pressure remain controversial. Therefore, we studied the effects of 22-week-long training on blood pressure, arterial reactivity, and metabolic abnormalities in a model of genetic obesity and moderate hypertension. METHODS Obese and lean Zucker rats were subjected to treadmill exercise from 8 to 30 weeks of age. Blood pressures were measured by the tail-cuff method, and urine was collected in metabolic cages. At the end of the study, the samples for biochemical determinations were taken, and reactivity of isolated mesenteric and carotid arterial rings was examined in standard organ chambers. RESULTS The exercise prevented the elevation of blood pressure which was observed in non-exercised obese Zucker rats, and also reduced blood pressure in the lean rats. The relaxations of norepinephrine-preconstricted mesenteric and carotid arterial rings to acetylcholine and nitroprusside were clearly improved by exercise in the obese rats. In the lean rats exercise enhanced vasorelaxation to nitroprusside in the mesenteric and carotid rings, and to acetylcholine in the carotid preparations. The exercise-induced improvement of endothelium-mediated dilatation to acetylcholine was abolished by nitric oxide synthesis inhibition with NG nitro-L-arginine methyl ester, but not by cyclooxygenase inhibition with diclofenac or functional inhibition of endothelium-dependent hyperpolarization by precontractions with KCl. The urinary excretion of the systemic prostacyclin metabolite (2,3-dinor-6-ketoprostaglandin F1 alpha) was increased two-fold by exercise in the obese and lean rats, whereas that of the thromboxane A2 metabolite (11-dehydrothromboxane B2) remained unaffected. Treadmill training reduced blood glucose, cholesterol, and triglycerides, but did not affect the high levels of insulin in obese Zucker rats. CONCLUSIONS These results suggest that the antihypertensive effect of long-term exercise in experimental obesity related hypertension is associated with improved vasodilatation. This is expressed as enhanced relaxation via endogenous and exogenous nitric oxide, and increased endothelial prostacyclin production. The improved control of arterial tone after training could be attributed to the alleviation of hyperlipidemia and insulin resistance, whereas hyperinsulinaemia per se remained unaffected.

Placental Glucose Transporters in Fetal Intrauterine Growth Retardation and Macrosomia

To investigate the role of placental glucose delivery in fetal growth, two glucose transporters (Glut3 and Glut4) were determined from term placentae. This was accomplished by immunoblotting from crude placental membrane samples from cases of fetal intrauterine growth retardation (IUGR, n = 6), macrosomia (n = 6), maternal diabetes mellitus (n = 4) and normal term (n = 8). Glut3 and Glut4 were detected in only very low numbers in all patient groups and there were no changes in their placental density, which suggests that the expression of these transporters is not involved in disorders of fetal growth. However, birth weight corresponded to placental weight, indicating that the total amount of Glut3 and Glut4 is reduced in IUGR and increased in macrosomia.

Effects of training and anabolic steroids on collagen synthesis in dog heart

SummaryThe effects of endurance training and anabolic steroid (Methandienone 1.5 mg · kg−1 p. o. daily) and their combination on regional collagen biosynthesis and concentration in the hearts of male beagle dogs were studied by measuring prolyl 4-hydroxylase (PH) activity and hydroxyproline (HYP) concentration. The PH (P<0.05) and HYP (P<0.05) were both greater in the subendocardinal layer than in the subepicardium (EPI) of the left ventricular wall in controls, whereas opposite gradients (P<0.05) were observed in the right ventricle. Endurance exercise caused an increase of PH activity in EPI of the left ventricular wall (P<0.01). The HYP concentration increased in both layers of the right ventricle in the exercise plus steroid group (P<0.05). The results suggest that transmural differences exist in the rate of collagen synthesis and concentration in canine cardiac ventricles and that endurance exercise may accelerate collagen synthesis in EPI of the left ventricle and the combination of exercise and anabolic steroid causes an increase in collagen concentration in the right ventricular wall.

Activities of antioxidant enzymes and lipid peroxidation in endometrial cancer

Antioxidant enzyme activities and lipid peroxidation were analysed in normal endometrium and endometrial cancer tissues from Finnish and Japanese patients. The catalase and glutathione peroxidase activities of normal endometrium were significantly lower in Finns than in Japanese. Lipid peroxidation was slightly higher in endometrial cancer as compared with normal endometrium both in the Finns and in the Japanese. When cancer tissues were compared with normal endometrium both in Finns and Japanese the activity of superoxide dismutase was significantly lower in cancer tissue than in normal endometrium. In Finns glutathione S-transferase activity was also lower in endometrial cancer tissue than in normal endometrium, and a similar tendency was also found in Japanese. This study suggests that endometrial cancer tissue is associated with an impaired enzymic antioxidant defence system.

TGF-β induces the expression of SAP30L, a novel nuclear protein

BackgroundWe have previously set up an in vitro mesenchymal-epithelial cell co-culture model which mimics the intestinal crypt villus axis biology in terms of epithelial cell differentiation. In this model the fibroblast-induced epithelial cell differentiation from secretory crypt cells to absorptive enterocytes is mediated via transforming growth factor-β (TGF-β), the major inhibitory regulator of epithelial cell proliferation known to induce differentiation in intestinal epithelial cells. The aim of this study was to identify novel genes whose products would play a role in this TGF-β-induced differentiation.ResultsDifferential display analysis resulted in the identification of a novel TGF-β upregulated mRNA species, the Sin3-associated protein 30-like, SAP30L. The mRNA is expressed in several human tissues and codes for a nuclear protein of 183 amino acids 70% identical with Sin3 associated protein 30 (SAP30). The predicted nuclear localization signal of SAP30L is sufficient for nuclear transport of the protein although mutating it does not completely remove SAP30L from the nuclei. In the nuclei SAP30L concentrates in small bodies which were shown by immunohistochemistry to colocalize with PML bodies only partially.ConclusionsBy reason of its nuclear localization and close homology to SAP30 we believe that SAP30L might have a role in recruiting the Sin3-histone deacetylase complex to specific corepressor complexes in response to TGF-β, leading to the silencing of proliferation-driving genes in the differentiating intestinal epithelial cells.

Dissociation of the effects of training on oxidative metabolism, glucose utilisation and GLUT4 levels in skeletal muscle of streptozotocin-diabetic rats

The effects of long-term, moderate physical exercise on in vivo glucose uptake, levels of two glucose transporter proteins (GLUT1 and GLUT4) and activities of various key enzymes of energy metabolism were measured in skeletal muscle from streptozotocin-diabetic rats. Diabetes (12–16 weeks) reduced the in vivo glucose uptake (glucose metabolic index, GMI) in muscle containing mainly type I fibres by 55% but had no effect in muscles containing mainly type IIa and IIb fibres. GMI was increased in the diabetic white skeletal muscle (mainly type IIb fibres) by more than 120%. In contrast to the complex changes in GMI, GLUT4 levels were reduced in all types of skeletal muscle from diabetic rats with no change in GLUT1 levels. Exercise training had no effects on GMI or the glucose transporter levels. Streptozotocin induced diabetes significantly reduced the oxidative capacity of skeletal muscle assayed as the activities of citrate synthase, succinate dehydrogenase and cytochrome c oxidase. Training increased the activities of oxidative enzymes, with this increase being more prominent in the diabetic animals. The present data indicate that long-term streptozotocin-induced diabetes decreases oxidative metabolic capacity and GLUT4 protein levels in skeletal muscle, but that the changes of glucose transport largely depend on the fibre type composition. Moderate training fully reverses the effect of insulinopenia and hyperglycaemia on muscle oxidative metabolism. In contrast to the previous suggestions, the expression of GLUT4 is not correlated with the capacity of oxidative metabolism in skeletal muscle of streptozotocin-diabetic rats.

Differentially expressed CC3/TIP30 and rab11 along in vivo and in vitro intestinal epithelial cell crypt-villus axis.

We have previously shown that transforming growth factor-beta1 (TGF-beta1) is involved in the fibroblast-induced organization and differentiation of transformed phenotypically crypt-like T84 intestinal epithelial cells into absorptive enterocyte-like cells, when cultured within a three-dimensional collagen gel. We have used differential display polymerase chain reaction to find genes that are either up- or downregulated by TGF-beta in the T84 cells cultured in three-dimensional collagen gel and then studied how these in vitro differentially expressed genes are expressed in vivo in the small intestinal crypt-villus axis. We found that the TGF-beta1-treated T84 cells, like the villus tip enterocytes, expressed increased levels of CC3/TIP30 when compared to the undifferentiated cells. Furthermore, the expression of rab11 showed the opposite pattern, being higher in the undifferentiated cells both in vivo and in vitro. We conclude that the three-dimensional cell culture model where TGF-beta induces organization and differentiation of secretory T84 epithelial cells makes it possible to find up- and downregulated transcripts that also play a role in the human small intestinal crypt-villus axis.

Enterochromaffin cell density in the gastric mucosa of patients with chronic renal failure.

Thirty patients with chronic renal failure (CRF) and 30 age‐ and sex‐matched controls were assessed for gastrointestinal diseases by gastroscopy, serum gastrin determination, and routine clinical and laboratory evaluation. Biopsy specimens from their gastric oxyntic mucosa were immunohistochemically stained with monoclonal antibodies against serotonin (5‐hydroxytryptamine) and chromogranin A, the latter staining all gastric endocrine cells, the former disclosing serotonin‐containing enterochromaffin (EC) cells only. The average EC cell density (cells/mm2) in the CRF patients was significantly lower than in the controls: 2.6 vs 12.9 (p=0.0005). The EC cell counts also correlated negatively with serum gastrin values (p=0.0031). The densities of the chromogranin‐positive cells did not differ between CRF patients (74 cells/mm2) and controls (76 cells/mm2) (p=0.7559). We conclude that, in addition to the previously known findings of hypoacidity, persistent hypergastrinaemia, and G and parietal cell hyperplasia, CRF also reduces the number of oxyntic EC cells. The negative correlation between EC cell density and serum gastrin levels reflects the complex interplay between different endocrinological activities in the gastrointestinal tract.