G. Fleckensteingrun et al., PROGRESSION AND REGRESSION BY VERAPAMIL OF VITAMIN-D-3-INDUCED CALCIFIC MEDIAL DEGENERATION IN CORONARY-ARTERIES OF RATS, Journal of cardiovascular pharmacology, 26(2), 1995, pp. 207-213
Vitamin D-3-induced mural calcification represents an animal model for
investigating experimental calcium (Ca) overload and calcification of
arterial walls. In this study, long-term progression of calcific dege
neration in coronary arteries of rats after one intoxication with vita
min D-3 was examined, as well as possible regression of preestablished
mural Ca overload with the Ca antagonist verapamil, Sprague-Dawley ra
ts were treated with one intramuscular (i.m.) overdose of vitamin D-3
[300,000 IU/kg body weight (b.w.)]. Oral verapamil therapy (100 mg/kg/
day b.w. for 24 weeks) was initiated 14 days after the vitamin D-3 int
oxication, Arteriosclerotic alterations were verified by microchemical
analyses of tissue Ca and of cholesterol contents with atomic absorpt
ion spectroscopy (special graphite tube technique) and gas chromatogra
phy, respectively, and by standard histological techniques. Serum lipi
ds were determined by sequential ultracentrifugation. Between week 3 a
nd week 26 after the vitamin D-3 injection, a progressive Ca incorpora
tion from 448.8 +/- 110 to 1,310 +/- 166.3% of control values (i.e., c
oronary Ca content in 32-week-old untreated control rats = 100%) was o
bserved, associated with calcific morphological lesions, and reactive
intimal plaque formation. Verapamil prevented this progression and ind
uced a regression of preestablished mural Ca overload. Therefore, the
coronary Ca content after 24 weeks of verapamil treatment amounted to
only 146.3 +/- 53.8% of controls. The data indicate that an initial ca
lcific lesion of coronary arteries may serve as crystallization nucleu
s for advancing Ca overload and morphological alterations. Damping of
transmembrane Ca influx into vascular smooth muscle cells by verapamil
, possibly in concert with a direct interaction of verapamil with extr
acellular Ca binding sites, halts progression and obviously favors hea
ling processes responsible for the regression of preestablished lesion
s.