Local infusion of ouabain at 2 micrograms/min for 1 hour caused a 26% reduction in forearm blood flow and reduced the dilator response to potassium by 33%.
Does local infusion of ouabain alter forearm vascular resistance and dilator responses to potassium, verapamil, and sodium nitroprusside in normotensive men?
Acute depression of sodium pump activity by ouabain reproduces the increased resting vascular resistance and impaired response to potassium seen in hypertension, but does not explain the enhanced responsiveness to verapamil.
Effect estimate: 26% reduction
The effect of local infusion of ouabain into the forearm vascular bed has been examined in 15 normotensive male volunteers in an attempt to define the nature of the functional abnormalities of the resistance vessels in primary hypertension. Ouabain and other drugs were infused into the brachial artery and forearm blood flow was measured by venous occlusion plethysmography. Infusion of ouabain at 2 micrograms/min for 1 h caused a 26% reduction in forearm blood flow with a small rise in systemic arterial pressure; the increase in vascular resistance was unaffected by prior treatment with phentolamine. After infusion of ouabain the dilator response to potassium was reduced by 33% but the responses to verapamil and sodium nitroprusside were unchanged. The results show that acute depression of sodium pump activity by ouabain reproduces the increased resting resistance and impaired response to potassium that are seen in hypertension. It does not reproduce the relative enhancement of responsiveness to verapamil that is also observed in the resistance vessels of patients with hypertension and this abnormality must have some other cause.
Robinson et al. (Mon,) conducted a other in Primary hypertension (mechanisms) (n=15). Local infusion of ouabain was evaluated on Forearm blood flow (26% reduction). Local infusion of ouabain at 2 micrograms/min for 1 hour caused a 26% reduction in forearm blood flow and reduced the dilator response to potassium by 33%.