Decrease in blood flow and temperature of rat knee joint by calcium channel blockers in chronic inflammation

Introduction: The Blood flow increases in the inflamed joint induced by
Complete Freund’s Adjuvant (CFA). Since the anti-inflammatory effect of
calcium channel blockers have been shown in pervious studies, the present study
investigates the role of these blockers on the blood flow and temperature
(inflammation indices) in inflamed knee joint induced by CFA.
Methods: This experimental study was carried out in 8 groups of adult male rats. In
group I, 0.2 ml of CFA solution was injected into the right knee, and group II
received the same volume of normal saline. Group III to VIII received the same
volume of CFA solution, but seven days after injection of CFA to the end of study,
received the following drugs orally by oropharyngeal tubes. Group III
dimethylsulfoxide (the drugs solvent), group IV and V received low dose (100 μg/kg)
of verapamil and nifedipine respectively. Group VI and VII received high dose (800
μg/kg) of verapamil and nifedipine respectively, and group VIII was treated with
ibuprofen (15mg/kg). The changes in blood flow and local temperature of the
animal’s knee joint were measured for 28 days after CFA injection.
Results: CFA injection increased blood flow significantly in all 28 days
compared to day zero, where as at seventh day increase in blood flow was
121.8±6.1 percent. Low dose of verapamil and nifedipine increased CFAinduced
blood flow. The high dose of verapamil and nifedipine also diminished
the blood flow of the knee. The inhibition effect of these blockers on knee joint
blood flow was comparable to ibuprofen. Decrease in temperature by different
doses of verapamil and nifedipine were not significant.
Conclusion: The results of this study show that calcium channel blockers inhibit
the increased blood flow and temperature in chronic inflammation induced by
CFA injection in the inflamed region. So these blockers possibly reduce the
chronic inflammation by this mechanism.