Enhanced prostacyclin biosynthesis and decreased thromboxane formation by 3-dimethylamino 5-(2′,6′-dichlorobenzylidene) 6-methyl (4H)-pyridazine (PC 89).

This research studies the effects of a drug called PC 89 on biosynthesis of two compounds: PG I2 and TX A2. It suggests that the drug enhances the formation of beneficial PG I2, inhibits the production of harmful TX A2 and could be valuable in treating heart conditions such as myocardial ischemia and atherosclerosis.

Study Details

• The researchers investigated the influence of 3-dimethylamino 5-(2′,6′-dichlorobenzylidene) 6-methyl (4H)-pyridazine, termed as PC 89, on the production of Prostacyclin (PG I2) and Thromboxane (TX A2).
• The enzymes and arachidonic acid used for this study were sourced from horse aorta and horse platelet microsomes.
• PC 89 was applied in varying concentrations, ranging from 1.10(-6) M to 1.10(-3) M.

Results

• Observations showed that the production of PG I2 was “dose-dependently” enhanced by PC 89, meaning the increase in PG I2 biosynthesis was proportional to the applied dose of PC 89.
• Specifically, the AD50 (median effective dose) was recorded as 6.8 X 10(-6) M +/- 1.2 X 10(-9) M.
• Concentration variation did not significantly affect Vmax (maximum rate of reaction). PC 89 improved the affinity of the enzyme for the substrate, contributing to the biosynthesis of PG I2.
• Additionally, it was found that PC 89 inhibited the biosynthesis of TX A2. The inhibition potency, measured by ID50, was recorded as 3.31 X 10(-3) M +/- 4.8 X 10(-7) M.
• The inhibitory action on TX A2 biosynthesis by PC 89 was found not to be of a competitive type, meaning it doesn’t compete with the substrate for binding to the enzyme’s active site.

Implications

• The unique dual action of PC 89, enhancing the production of beneficial PG I2 and inhibiting the production of potentially harmful TX A2, indicates its therapeutic potential.
• The researchers concluded that this compound could be an effective drug for treating myocardial ischemia (inadequate blood supply to the heart muscle) and atherosclerosis (build-up of plaques in the arteries), highlighting the importance of further research into its application and effectiveness.