Vasodilation to Bradykinin Is Mediated by an Ouabain-Sensitive Pathway as a Compensatory Mechanism for Impaired Nitric Oxide Availability in Essential Hypertensive Patients
Why the study?
Does an ouabain-sensitive pathway mediate vasodilation to bradykinin in patients with essential hypertension?
Population
46 subjects total, comprising 24 patients with essential hypertension and 22 healthy normotensive controls.
Comparison
Intrabrachial infusion of bradykinin in the… vs Intrabrachial infusion of saline and comparison…
Design
Cross-sectional
Authors
Discussion
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Implication
Ouabain-sensitive pathways may compensate for NO-impaired vasodilation in hypertension; leaves open therapeutic targeting pending prospective studies.
Key Points
- The study aims to identify the mechanisms behind NO-independent vasodilation to bradykinin in essential hypertension.
- Involved 16 healthy subjects and 16 patients with essential hypertension; utilized strain-gauge plethysmography.
- Measured forearm blood flow during bradykinin infusion with interventions including L-NMMA and ouabain.
- Repeat assessments in adjunctive hypertensive patients with vitamin C administration to scavenge oxygen free radicals.
- In hypertensive patients, vasodilation to bradykinin was significantly reduced by ouabain (p<0.05) but not by L-NMMA.
- Vitamin C restored the L-NMMA-induced blockade of vasodilation to bradykinin in hypertensive patients.
- In healthy controls, vasodilation remained inhibited by simultaneous ouabain infusion.
Structured PICO
Does an ouabain-sensitive pathway mediate vasodilation to bradykinin in patients with essential hypertension?
P
Population
46 subjects total, comprising 24 patients with essential hypertension and 22 healthy normotensive controls.
I
Intervention
Intrabrachial infusion of bradykinin (5, 15, or 50 ng/100 mL of forearm tissue per minute) in the presence of L-NMMA (100 microg/100 mL/min), ouabain (0.7 microg/100 mL/min), or vitamin C (8 mg/100 mL/min).
C
Comparator
Intrabrachial infusion of saline and comparison between hypertensive patients and healthy controls.
O
Outcome
Modifications in forearm blood flow measured by strain-gauge plethysmography.surrogate
In essential hypertension, impaired NO-dependent vasodilation is compensated by an alternative ouabain-sensitive pathway, likely involving endothelium-dependent hyperpolarization, which can be reversed by vitamin C.
Cite This Study
Taddei et al. (1999) studied this question.