HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

In situ detection of cyclic AMP-phosphodiesterase activity in the heart of Lewis and Sprague-Dawley rats: the effect of restraint stress or amphetamine application

L. Okruhlicová1, V. Klenerová2, S. Hynie2 and P. Sída2

1Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic and 2Charles University in Prague, First Medical Faculty, Institute of Pharmacology, Prague, Czech Republic

Offprint requests to: L. Okruhlicová, PhD., Institute for Heart Research, Slovak Academy of Sciences, Dubravska cesta 9, 840 05 Bratislava 45, PO BOX 104, Slovak Republic, e-mail: usrdokru@savba.sk

 

Summary. Cyclic AMP plays an important role in heart functions under normal as well as pathological conditions. Since phosphodiesterase (PDE), responsible for the hydrolysis of cAMP, is equally important as synthesizing adenylyl cyclase, we decided to determine its activity by cytochemical procedure after exposure of rats to restraint stress or an acute dose of amphetamine. Sprague-Dawley (S-D) and Lewis (LE) rats, the latter known to have a deficient hypothalamo-pituitary-adrenal axis activity, were used in order to disclose the possible significance of rat strain on PDE activity. Animals were divided into 3 groups: controls, rats treated with an acute dose of amphetamine (8 mg/kg, i.p., for 60 min) and rats under restraint stress for 60 min. Control hearts of both strains revealed PDE activity on sarcolemma of cardiomyocytes and plasmalemma of endothelial cells of microvessels. In LE rats we observed an additional enzyme reaction in junctional sarcoplasmic reticulum. In addition, cardiomyocytes of LE rats revealed a higher PDE activity when compared to S-D rats. Restraint stress decreased PDE activity in cardiomyocytes of LE rats while amphetamine markedly inhibited enzyme activity in cardiomyocytes of S-D rats. Endothelial PDE was more resistant to stress. Our results indicate differences in PDE localization and variations in sensitivity of myocardial cAMP-PDE of LE and S-D rat strains to restraint stress and amphetamine application. Histol. Histopathol. 19, 719-726 (2004)

Key words: Phosphodiesterase, Cytochemistry, Heart, Restraint stress, Amphetamine

DOI: 10.14670/HH-19.719