Related Experiment Videos
Influence of hypotension on cochlear blood flow in polycythemic condition
Y Ohinata1, K Makimoto, H Takahashi
1Department of Otolaryngology, Saiseikai Nakatsu Hospital, Osaka, Japan.
Insights
Hypotension induced by acebutolol hydrochloride (AH) significantly reduced cochlear blood flow (CBF), especially in guinea pigs with high hematocrit. This highlights the inner ear
Area of Science:
- Otolaryngology
- Cardiovascular Physiology
- Pharmacology
Background:
- Hypotension can affect inner ear function.
- Hematocrit levels influence blood viscosity and flow.
- Beta-receptor antagonists can induce hypotension.
Purpose of the Study:
- To investigate the impact of acebutolol hydrochloride-induced hypotension on cochlear blood flow (CBF).
- To determine how varying hematocrit levels affect the relationship between hypotension and CBF.
- To assess the consequences of altered CBF on oxygen transport capacity in the inner ear.
Main Methods:
- Administered acebutolol hydrochloride (AH) to guinea pigs with different hematocrit values.
- Monitored mean blood pressure and cochlear blood flow (CBF) responses.
- Calculated oxygen transport capacity based on measured CBF and hematocrit.
Main Results:
- AH infusion uniformly decreased mean blood pressure across all hematocrit groups.
- The reduction in CBF was more pronounced at higher hematocrit levels.
- Oxygen transport capacity was diminished post-AH infusion, with a greater deficit observed at higher hematocrits.
Conclusions:
- The microcirculation of the inner ear is sensitive to perfusion pressure changes, particularly at high hematocrit levels.
- High hematocrit exacerbates the negative impact of hypotension on cochlear blood flow and oxygen supply.
- These findings have implications for understanding inner ear vulnerability during hypotensive events in conditions of polycythemia.
Abstract:
We examined the influence of hypotension by infusion of acebutolol hydrochloride (AH), a cardioselective beta-receptor antagonist, on cochlear blood flow in guinea pigs with various hematocrit values. AH infusion lowered the mean blood pressure to almost the same degree in all animals, regardless of the hematocrit level. The degree of the concomitant decrease of CBF varied with the hematocrit, being greater in animals with a higher hematocrit. In those with the highest hematocrit CBF did not return to the initial level. From these values we calculated the O2 transport capacity after AH infusion and found it to be lower than in animals without AH infusion. The difference was greater at higher hematocrits. These findings suggest that the microcirculation of the inner ear is responsive to transient decreases of perfusion pressure at high hematocrits.