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Biomedical subjects

J Ohisalo

Publications and source records attributed to J Ohisalo.

4 recordsLinked to original sources
PubMed2001

Decreased expression of phospholamban is not associated with lower beta-adrenergic activation in rat atria.

The aim of the study was to find out whether low phospholamban level in atria as compared with ventricles is associated with differences in sarcoplasmic reticular Ca2+-uptake and contractile performance. Relationship between phospholamban and beta-adrenergic stimulation in rat left atria and papillary muscles were examined by means of contractile measurements, sarcoplasmic reticular oxalate-supported Ca2+-uptake, and Western blotting of phosphorylated phospholamban. Phosphoprotein determination after beta-adrenergic stimulation demonstrated that the levels of Ser16 and Thr17 phosphorylated phospholamban in atria remained at about one-third of that in ventricles. However, comparison of sarcoplasmic reticular Ca2+-uptake in control and isoproterenol perfused preparations demonstrated that the effect of beta-adrenergic stimulation on sarcoplasmic reticular Ca2+-uptake was stronger in atrial preparations. Moreover, atria responded to isoproterenol with much larger increases in developed tension, contractility and relaxation rates than papillary muscles. Thus, despite lower level of phospholamban, the beta-adrenergic activation of sarcoplasmic reticular Ca2+-uptake and contractile indices are higher in atria.

Adrenergic beta-Agonists↗
PubMed1996

Hepatotoxicity and absorption of extrahepatic acetaldehyde in rats.

Acetaldehyde, the first metabolite of ethanol oxidation, has been proposed as a major initiating factor in ethanol-induced liver injury. The aims of this study were to examine whether acetaldehyde is absorbable from the digestive tract and whether, when delivered chronically in drinking water, it is capable of inducing liver injury in rats. Acetaldehyde concentrations in the rat portal and peripheral blood were measured by head space gas chromatography after intragastric (5 ml) and intracolonic (3 ml) administration of 20 mM acetaldehyde solution. In the hepatotoxicity study, rats were exposed to acetaldehyde (20 and 120 mM) delivered in drinking water for 11 weeks and histopathological changes in the liver were morphometrically assessed. Peak blood acetaldehyde levels were found at 5 min after acetaldehyde infusion and were 235 +/- 11 microM (mean +/- SE) after intragastric and 344 +/- 83 microM after intracolonic infusion of 20 mM acetaldehyde solution. The exposure of rats to 120 mM acetaldehyde solution for 11 weeks resulted in the development of fatty liver and inflammatory changes. Morphometric analysis showed significantly more fat accumulation in rats receiving 120 mM acetaldehyde solution (85 +/- 2 per cent of hepatocytes occupied by fat) than in rats receiving 20 mM acetaldehyde solution (38 +/- 11 per cent) or in controls (36 +/- 10 per cent). The dose of extrahepatic acetaldehyde (500 mg/kg per day) producing liver injury corresponds to only around 3 per cent of that derived from hepatic ethanol oxidation in animals receiving an ethanol-containing totally liquid diet (15 g/kg per day). These results indicate that acetaldehyde delivered via the digestive tract can reach the liver by the portal circulation and that acetaldehyde of extrahepatic origin appears to be more hepatotoxic than acetaldehyde formed during ethanol oxidation within the liver.

Absorption↗
PubMed1984

Persistent tyrosinemia associated with low activity of tyrosine aminotransferase.

A son of related Turkish parents had grossly elevated serum tyrosine concentration and excreted tyrosine and p-hydroxyphenolic acids into the urine, whereas neither succinylacetone nor succinylacetoacetate could be demonstrated. The tyrosine concentration was normalized by a proper diet. This was not followed strictly at home. During the first 2 years of life, the patient had severe undulating nystagmus that disappeared later. No skin lesions were present and there was only slight corneal clouding of the eyes. At the age of 5, the patient had attained the maturity of a 4-year-old, showing a balanced profile. Specific tyrosine aminotransferase (EC 2.6.1.5) was present in the liver; the Km value for tyrosine was normal. However, the total activity was less than 10% of normal, a situation similar to that observed in fetal human liver. A younger sister of the patient also has tyrosinemia and low hepatic tyrosine aminotransferase activity.

Amino Acid Metabolism, Inborn Errors↗