DNA synthesis in isolated arteries of normotensive and hypertensive rats: effects of the endothelium.
OBJECTIVE
To compare DNA synthesis in isolated arteries of normotensive and hypertensive rats and to evaluate whether removal of the endothelium affects this process.


METHODS
Carotid and renal artery segments were isolated from normotensive Wistar, Wistar-Kyoto (WKY) and Sprague-Dawley rats, and from spontaneously hypertensive rats (SHR), transgenic Sprague-Dawley rats harbouring the mouse Ren-2 gene and from WKY rats rendered hypertensive by aortic coarctation.


METHODS
Artery segments were exposed in vitro to serum with or without previous gentle removal of the endothelium. Nuclear incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine was visualized by immunocytochemistry and the percentage of labelled medial nuclei was determined.


RESULTS
In both types of artery, obtained from 6-week-old WKY rats and from 6-week-old SHR, removal of endothelium increased the percentage of 5-bromo-2'-deoxyuridine-labelled medial nuclei (L%). Also, in the arteries of 20-week-old Wistar rats, WKY rats and WKY rats rendered hypertensive by aortic coarctation and in vessels of 11-week-old Sprague-Dawley rats and Sprague-Dawley rats harbouring the mouse Ren-2 gene, removal of endothelium increased L%. Conversely, in the arteries of 20-week-old SHR removal of the endothelium did not alter L%. Furthermore, maximally stimulated DNA synthesis was considerably smaller in de-endothelialized arteries of adult SHR than in denuded vessels from the other strains and models.


CONCLUSIONS
These findings confirm that the endothelium can reduce DNA synthesis in the intact rat arterial smooth muscle. This effect is not modified by hypertension, but is selectively reduced in the arteries of adult SHR.
Department of Pharmacology, University of Limburg, Maastricht, The Netherlands.
P M
PM
Schiffers
G E
GE
Fazzi
G M
GM
Janssen
M P
MP
Uitendaal
H A
HA
Struijker Boudier
J G
JG
De Mey
D000818:Animals; D030801:Animals, Genetically Modified; D001017:Aortic Coarctation / Q000150:complications; D001158:Arteries / Q000378:metabolism*; D002339:Carotid Arteries / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism; D006973:Hypertension / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D014176:Protein Biosynthesis; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley; D012077:Renal Artery / Q000378:metabolism
D004247:DNA