Platelet lipoxygenase in spontaneously hypertensive rats

Area of Science:

• Cardiovascular Research
• Biochemistry
• Pharmacology

Background:

• The nonselective lipoxygenase inhibitor phenidone demonstrates hypotensive effects in spontaneously hypertensive rats (SHR).
• Platelet 12-hydroxyeicosatetraenoic acid (12-HETE) is a product of the 12-lipoxygenase pathway.

Purpose of the Study:

• To investigate the relationship between platelet 12-HETE production and intra-arterial blood pressure in SHR and Wistar-Kyoto rats (WKY).
• To assess the impact of inhibiting 12-lipoxygenase on blood pressure and 12-HETE generation in hypertensive rats.

Main Methods:

• Cross-sectional analysis and acute pharmacological intervention in SHR and WKY rats.
• Measurement of basal 12-HETE generation rate in platelets.
• Administration of the specific 12-lipoxygenase inhibitor cinnamyl-3,4-dihydroxycyanocinnamate and captopril.
• Monitoring of intra-arterial blood pressure.

Main Results:

• Platelets from SHR exhibited a 3.7-fold higher basal 12-HETE generation rate compared to WKY rats (P < .01).
• Systolic arterial pressure positively correlated with platelet 12-HETE formation rate (r = .70, P < .001).
• Cinnamyl-3,4-dihydroxycyanocinnamate significantly reduced blood pressure and 12-HETE production in SHR, with blood pressure recovery paralleling increased 12-HETE levels. Captopril lowered blood pressure without affecting 12-HETE generation.

Conclusions:

• Hypertension in SHR is associated with elevated platelet 12-HETE production.
• Acute blood pressure reduction via lipoxygenase inhibition, but not ACE inhibition, is accompanied by decreased 12-HETE production.
• Increased 12-lipoxygenase activity in SHR may contribute to maintaining elevated arterial pressure.