Splitting fibres to clean up a bloody mess

Setting a new task for calcium channel blockers could open a novel avenue for hypertension treatment

By Brian Hoyle

Shadowy and elusive, hypertension and its partner in crime, vascular damage, are thorns in the sides of doctors feeling frustrated and helpless when that unexpected heart attack or stoke strikes down a patient. A new report in the March issue of the American Journal of Hypertension may help to throw some light on this troubling issue and could open a promising new avenue of hypertension treatment.

The study shows that calcium channel blockers (CCBs), already used to relax blood vessels, can increase the amount of an enzyme that degrades vessel-harming fibrous tissue. Lead author Dr Alexandra Zervoudaki of Athens' Hippokratio Hospital, reasoned that CCBs' effects might be partially due to their ability to control the activity of matrix metalloproteinases (MMPs), enzymes that can chew up fibrous depositions. Dr Zervoudaki and her colleagues treated 72 hypertension patients for six months with one of two CCBs, felodipine and diltiazem. Levels of two MMPs � MMP-2 and MMP-9 � were measured before and after treatment and compared to levels in 45 patients without hypertension.

Before the treatment began, MMP-2 and MMP-9 levels were significantly lower in the hypertensive group. After a six-month course of either drug, the group's blood pressure was normalized. These welcome improvements come on the heels of a significant increase in MMP-2, but not MMP-9, levels in felodipine-treated patients. Diltiazem-treated patients showed no significant increase in MMP levels despite improved blood pressures.

Unfortunately, the establishment of an unequivocal relationship between MMP-2 and fibrous buildup relief is still lacking, and the study authors concluded that "whether a possible beneficial vascular protective effect of some hypertensive agents could be translated into improved outcome in hypertension, beyond the effect of lowering blood pressure, has not yet been clarified." Nonetheless, any research showing a decrease in high blood pressure is good news to the almost 1.5 million Canadians over 65 known to have the malady.