Key result
Hydralazine acetonide produces greater dose-dependent decreases in K+-induced tone versus hydralazine in rabbit aortas.
Why the study?
The intrinsic vascular smooth muscle activity of hydralazine acetonide compared to hydralazine and its contribution to hypotensive effects was unclear.
p-value: p=<0.05
Hydralazine acetonide demonstrates greater intrinsic vasodilator activity on vascular smooth muscle compared to its parent compound, hydralazine, in an in vitro model.
Does not support clinical adoption of hydralazine acetonide; leaves open translation of greater in vitro potency to human therapy.
Dose-response relationships to K+ were determined in isolated strips of rabbit aorta. 2. K+ contractures were induced by 30 mM K+ in paired strips from individual animals. The effects of hydralazine and hydralazine acetone hydrazone (hydralazine acetonide) on these contractures were studied. 3. Hydralazine and hydralazine acetonide both produced dose-dependent decreases of K+-induced tone. Threshold concentrations for hydralazine were 11.89 +/- 4.5 X 10(-5) M (mean +/- s.d.) and for hydralazine actonide 9.7 +/- 4.6 X 10(-5) M (0.5 less than P less than 0.4). 4. The magnitude of the effect of hydralazine acetonide was greater than that of hydralazine at all concentrations above threshold, as reflected in a significant difference (P less than 0.05) in the slopes of dose-response curves to the two treatments. The vasodilator effects of hydralazine and the acetonide were terminated by washout of the bath. 5. The differences in effect were not due to instability of hydralazine under in vitro conditions. 6. It is concluded that hydralazine acetonide has intrinsic activity on vascular smooth muscle which differs significantly from that of the parent compound and that this may contribute to the hypotensive effects which follow administration of the parent compound.
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Barron et al. (1977) studied this question. Hydralazine acetonide vs. Hydralazine was evaluated on Dose-dependent decreases of K+-induced tone (p=<0.05). Hydralazine acetonide produced a significantly greater dose-dependent decrease in K+-induced tone in rabbit aorta strips compared to hydralazine at concentrations above threshold (P<0.05).