ISSN:
1420-908X
Keywords:
β-adrenergic receptor
;
cAMP
;
Endothelial cells
;
Smooth muscle cells
;
Theophylline
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Activation of vascularβ-adrenergic receptors prevents an increase in vascular permeability caused by free radicals or inflammatory peptides. Methylxanthines seem to have similar protective effects on vascular endothelium. In the present study we investigated the effect of theophylline on theβ-adrenergic receptor expression and cAMP concentrations in cultured endothelial and smooth muscle cells from bovine aorta. Comparable values forβ-receptor density and binding affinity were detected in both cell types. Isoproterenol induced significant downregulation ofβ-receptors in endothelial (BAEC: −60.5%) and smooth muscle cells (BASMC: −52.5%; P 〈 0.01). Incubation of endothelial cells with theophylline (4 µg/ml and 40 µg/ml) for 24 hours did not affectβ-receptor expression, whereas in smooth muscle cells theβ-receptor density was reduced for −31.5% and −28.7, respectively. In endothelial cells a transient effect on cAMP concentrations was observed after stimulation with isoproterenol (1 µM), but no effect was found in theophylline treated endothelial cells. Stimulation of intact smooth muscle cells with isoproterenol and theophylline (4 µg/ml and 40 µg/ml) resulted in a significant increase of cAMP concentrations after 60 and 240 minutes. The present data suggest a novel, celltype specific effect of theophylline on theβ-adrenergic receptor expression in vascular smooth muscle cells in vitro.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01796262
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