Effect of cigarette smoking on hypoxic pulmonary vasoconstriction and its relation to animal species and period of smoking

Effects of 3,4-dihydroxyacetophenone (3,4-DHAP) on hypoxic pulmonary and systemic vascular response in dogs

The effects of 3,4-DHAP on hypoxic pulmonary and systemic vascular responses were studied in anaesthetized dogs. The percentage change in pulmonary vascular resistance (delta PVR %) and that in systemic vascular resistance (delta SVR %) induced by 5 min hypoxia decreased significantly. 3,4-DHAP in doses of 1 mg/kg, 3 mg/kg, and 10 mg/kg i.v. caused a decrease in delta PVR% from the control value of 47.27 +/- 22.27% to 24.62 +/- 21.76%, 18.15 +/- 18.73%, and 24.10 +/- 19.76% respectively, and a decrease in delta SVR % from the control value of 12.91 +/- 7.39 % to -0.34 +/- 12.70%, -2.11 +/- 12.76%, and -2.37 +/- 15.52 % respectively. The results showed that 3,4-DHAP could decrease the hypoxic responses of pulmonary and systemic blood vessels. But it did not change delta PVR % or delta SVR % in dose of 30 mg/kg, neither did it influence the heart rate, cardiac output or cerebral blood flow during hypoxia in all the doses used.

Effects of 3,4-dihydroxyacetophenone on hypoxic vasoconstriction in isolated pulmonary and basilar arterial rings

The effects of 3,4-DHAP on hypoxic vasoconstriction response in pulmonary (PA) and basilar arterial (BA) rings of rabbits and their mechanism were compared in vitro. 3,4-DHAP in different concentration (2.64 x 10(-4), 7.92 x 10(-4), 2.376 x 10(-3) mol/L) decreased the basal tone of PA rings by 32.39 +/- 9.4 mg, 68.96 +/- 26.54 mg and 145.60 +/- 58.07 mg respectively, while the tension of the BA rings was decreased by 13.80 +/- 5.08 mg, 17.18 +/- 3.36 mg and 25.00 +/- 4.02 mg respectively. In PA rings it also decreased the percentage increase in tension induced by hypoxia (TIH%) from the control value 48.82 +/- 5.75% to 10.02 +/- 3.62%, 2.14 +/- 0.96%, and 0.00% respectively, while in BA rings from 27.27 +/- 5.78% to 11.23 +/- 2.71%, 7.49 +/- 1.62%, and 1.45 +/- 1.13% respectively. The effects of 3, 4-DHAP on TIH% were partially blocked by indomethacin 10 M and L-NAME 10 M. The results showed that 3, 4-DHAP can decrease the hypoxic pulmonary and basilar vasoconstriction in vitro, which can be partially inhibited by cyclooxygenase inhibitor and NO/EDRF inhibitor.