Hydrogen sulfide mediates vasoactivity in an O2-dependent manner

Area of Science:

• Biochemistry
• Physiology
• Vascular Biology

Background:

• Hydrogen sulfide (H(2)S) acts as a signaling molecule in vascular cells, similar to nitric oxide (NO).
• H(2)S modulates protein function via thiol modifications and interacts with targets like K(+) channels and heme proteins.
• The influence of oxygen (O(2)) on H(2)S reactions in the vasculature is understudied, despite O(2) altering experimental conditions.

Purpose of the Study:

• To investigate the hypothesis that the vascular effects of H(2)S are dependent on oxygen levels.
• To elucidate the role of oxygen concentration in mediating H(2)S-induced vascular responses.

Main Methods:

• Real-time measurement of H(2)S and O(2) levels using a novel polarographic H(2)S sensor.
• Vessel tension and respirometry experiments were conducted to assess vascular responses.
• Experiments were performed under varying oxygen concentrations to simulate physiological and high O(2) conditions.

Main Results:

• In rat aorta, H(2)S induced rapid contraction at high O(2) levels.
• Conversely, the same H(2)S concentrations mediated rapid relaxation at lower, physiological O(2) levels.
• The vasoconstrictive effect at high O(2) suggests a potential role for H(2)S oxidation products.

Conclusions:

• The vascular actions of H(2)S are significantly modulated by oxygen availability.
• Oxygen-dependent effects of H(2)S may involve vasoactive oxidation products.
• These findings highlight the importance of considering oxygen levels when studying H(2)S in vascular physiology and disease.