Lipoxygenase-dependent mechanisms in hypertension

Area of Science:

• Cardiovascular Physiology
• Biochemistry

Background:

• Hypertension is associated with vascular dysfunction.
• Lipoxygenase (LOX) pathways are implicated in cardiovascular diseases.

Purpose of the Study:

• To investigate the role of lipoxygenase products in aortic smooth muscle contraction and blood pressure regulation in a rat model of hypertension.
• To determine if lipoxygenase inhibition affects basal vascular tone and blood pressure.

Main Methods:

• Aortic coarctation was used to induce hypertension in rats.
• Western blotting was used to measure 12-lipoxygenase protein levels in aortic cytosolic fractions.
• Aortic rings were used to assess basal tone, and its reduction by lipoxygenase inhibitors cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate (CDC) and 5,8,11-eicosatriynoic acid (ETI).
• The effect of CDC on blood pressure was measured in normotensive and hypertensive rats, with and without indomethacin or prostaglandin I2 antibodies.

Main Results:

• 12-lipoxygenase protein was elevated in aortae from hypertensive rats compared to controls.
• Hypertensive rat aortic rings showed basal tone, significantly reduced by CDC and ETI.
• CDC administration lowered blood pressure in hypertensive rats but not normotensive rats.
• The blood pressure-lowering effect of CDC was diminished by indomethacin or prostaglandin I2 antibodies.

Conclusions:

• Lipoxygenase-derived products contribute to basal aortic smooth muscle tone and elevated blood pressure in rats with aortic coarctation-induced hypertension.
• The vasodepressor effect of CDC involves a mechanism dependent on vasodilatory prostaglandins.