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Cochlear blood flow in response to dilating agents.
Hear Res. 1992 Feb; 58(1):19-25.HR

Abstract

Reduced cochlear blood flow (CBF) has been implicated in various pathologies of the inner ear, including sudden deafness, noise-induced hearing loss and Meniere's disease. Thus the aim of some current therapeutic regimens to treat these conditions is to increase CBF and thereby improve oxygenation of the inner ear tissues. Most of the vasodilating agents in clinical use, however, do not have specific experimental evidence to support their effects on CBF. The hypotension which can follow systemic administration may limit their local effectiveness and general utility, just as it complicates the interpretation of the data in animal experiments. In the current study we investigated the effect of six agents, known for their systemic cardiovascular actions, on CBF: hydralazine, sodium nitroprusside, papaverine, nicotinic acid, verapamil and histamine. The effect of these drugs was studied after topical applications on the round window membrane (RWM) and systemic intravenous administrations. CBF was monitored with a laser Doppler flowmeter (LDF). Topical administration of sodium nitroprusside was the most effective in increasing CBF, followed, in order, by hydralazine and histamine. No change in CBF was observed for papaverine, verapamil or nicotinic acid. Systemic administrations of all the agents caused a marked decrease in blood pressure and variable effects on CBF. We discuss the CBF changes in relation to the different pharmacological mechanisms of action of each drug. The study demonstrates the effectiveness of topical application of vasodilating agents in increasing CBF.

Authors+Show Affiliations

Kresge Hearing Research Institute, University of Michigan, Ann Arbor 48109-0506.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

1559902

Citation

Ohlsén, K A., et al. "Cochlear Blood Flow in Response to Dilating Agents." Hearing Research, vol. 58, no. 1, 1992, pp. 19-25.
Ohlsén KA, Didier A, Baldwin D, et al. Cochlear blood flow in response to dilating agents. Hear Res. 1992;58(1):19-25.
Ohlsén, K. A., Didier, A., Baldwin, D., Miller, J. M., Nuttall, A. L., & Hultcrantz, E. (1992). Cochlear blood flow in response to dilating agents. Hearing Research, 58(1), 19-25.
Ohlsén KA, et al. Cochlear Blood Flow in Response to Dilating Agents. Hear Res. 1992;58(1):19-25. PubMed PMID: 1559902.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cochlear blood flow in response to dilating agents. AU - Ohlsén,K A, AU - Didier,A, AU - Baldwin,D, AU - Miller,J M, AU - Nuttall,A L, AU - Hultcrantz,E, PY - 1992/2/1/pubmed PY - 1992/2/1/medline PY - 1992/2/1/entrez SP - 19 EP - 25 JF - Hearing research JO - Hear. Res. VL - 58 IS - 1 N2 - Reduced cochlear blood flow (CBF) has been implicated in various pathologies of the inner ear, including sudden deafness, noise-induced hearing loss and Meniere's disease. Thus the aim of some current therapeutic regimens to treat these conditions is to increase CBF and thereby improve oxygenation of the inner ear tissues. Most of the vasodilating agents in clinical use, however, do not have specific experimental evidence to support their effects on CBF. The hypotension which can follow systemic administration may limit their local effectiveness and general utility, just as it complicates the interpretation of the data in animal experiments. In the current study we investigated the effect of six agents, known for their systemic cardiovascular actions, on CBF: hydralazine, sodium nitroprusside, papaverine, nicotinic acid, verapamil and histamine. The effect of these drugs was studied after topical applications on the round window membrane (RWM) and systemic intravenous administrations. CBF was monitored with a laser Doppler flowmeter (LDF). Topical administration of sodium nitroprusside was the most effective in increasing CBF, followed, in order, by hydralazine and histamine. No change in CBF was observed for papaverine, verapamil or nicotinic acid. Systemic administrations of all the agents caused a marked decrease in blood pressure and variable effects on CBF. We discuss the CBF changes in relation to the different pharmacological mechanisms of action of each drug. The study demonstrates the effectiveness of topical application of vasodilating agents in increasing CBF. SN - 0378-5955 UR - https://www.unboundmedicine.com/medline/citation/1559902/Cochlear_blood_flow_in_response_to_dilating_agents_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0378-5955(92)90004-7 DB - PRIME DP - Unbound Medicine ER -