Why the study?
Does inhalation of CO2 affect cochlear blood flow, blood pressure, and skin blood flow in anaesthetized guinea pigs?
Does inhalation of CO2 affect cochlear blood flow, blood pressure, and skin blood flow in anaesthetized guinea pigs?
High CO2 inhalation in guinea pigs increases cochlear blood flow and systemic blood pressure while decreasing skin blood flow, likely due to differential sympathetic and local vasodilatory effects.
No clinical translation from guinea pig data; leaves open CO2 effects on human cochlear perfusion.
The influence of carbon dioxide (CO2) on cochlear blood flow (CBF), blood pressure (SBP) and skin blood flow (SBF) was studied in anaesthetized guinea pigs. A transient acute respiratory acidosis was produced by inhalation of CO2 and oxygen (O2) gas mixtures. The blood flows were measured by laser Doppler flowmetry (LDF). High CO2 increased CBF and SBP, and decreased SBF in a dose-dependent manner. The responses of CBF, SBP and SBF to high CO2 were reversible. Our results indicate that high CO2 (and low pH) dilates the smooth muscle of the blood vessels, resulting in an increase in CBF. CO2 also activates the sympathetic nervous system in the whole body, producing an increase in SBP. The distribution of alpha-adrenergic fibres/receptors is abundant in skin and scarce in the cochlea. The constrictive effect on blood vessels is much greater in the skin than in the cochlea, thus our results showed a decrease in SBF during stimulation with higher CO2.
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Makoto Hasega Ayari Okamoto Ugnell (2000) studied this question.
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