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Sawamura S, Ogata G, Asai K, Razvina O, Ota T, Zhang Q, Madhurantakam S, Akiyama K, Ino D, Kanzaki S, Saiki T, Matsumoto Y, Moriyama M, Saijo Y, Horii A, Einaga Y, Hibino H. Analysis of Pharmacokinetics in the Cochlea of the Inner Ear. Front Pharmacol 2021; 12:633505. [PMID: 34012393 PMCID: PMC8128070 DOI: 10.3389/fphar.2021.633505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 04/16/2021] [Indexed: 11/14/2022] Open
Abstract
Hearing loss affects >5% of the global population and therefore, has a great social and clinical impact. Sensorineural hearing loss, which can be caused by different factors, such as acoustic trauma, aging, and administration of certain classes of drugs, stems primarily from a dysfunction of the cochlea in the inner ear. Few therapeutic strategies against sensorineural hearing loss are available. To develop effective treatments for this disease, it is crucial to precisely determine the behavior of ototoxic and therapeutic agents in the microenvironment of the cochlea in live animals. Since the 1980s, a number of studies have addressed this issue by different methodologies. However, there is much less information on pharmacokinetics in the cochlea than that in other organs; the delay in ontological pharmacology is likely due to technical difficulties with accessing the cochlea, a tiny organ that is encased with a bony wall and has a fine and complicated internal structure. In this review, we not only summarize the observations and insights obtained in classic and recent studies on pharmacokinetics in the cochlea but also describe relevant analytical techniques, with their strengths, limitations, and prospects.
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Affiliation(s)
- Seishiro Sawamura
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Genki Ogata
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kai Asai
- Department of Chemistry, Keio University, Yokohama, Japan
| | - Olga Razvina
- Department of Molecular Physiology, Niigata University School of Medicine, Niigata, Japan.,G-MedEx Office, Niigata University School of Medicine, Niigata, Japan
| | - Takeru Ota
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Qi Zhang
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan.,Department of Molecular Physiology, Niigata University School of Medicine, Niigata, Japan.,Department of Otolaryngology, Head and Neck Surgery Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Sasya Madhurantakam
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Koei Akiyama
- Department of Molecular Physiology, Niigata University School of Medicine, Niigata, Japan
| | - Daisuke Ino
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Sho Kanzaki
- Department of Otolaryngology, School of Medicine, Keio University, Tokyo, Japan
| | - Takuro Saiki
- Department of Medical Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yoshifumi Matsumoto
- Department of Medical Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masato Moriyama
- Department of Medical Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yasuo Saijo
- Department of Medical Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Arata Horii
- Department of Otolaryngology, Head and Neck Surgery Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yasuaki Einaga
- Department of Chemistry, Keio University, Yokohama, Japan
| | - Hiroshi Hibino
- Division of Glocal Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan.,AMED-CREST, AMED, Osaka, Japan
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Strimbu CE, Wang Y, Olson ES. Manipulation of the Endocochlear Potential Reveals Two Distinct Types of Cochlear Nonlinearity. Biophys J 2020; 119:2087-2101. [PMID: 33091378 DOI: 10.1016/j.bpj.2020.10.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/02/2020] [Accepted: 10/07/2020] [Indexed: 11/26/2022] Open
Abstract
The mammalian hearing organ, the cochlea, contains an active amplifier to boost the vibrational response to low level sounds. Hallmarks of this active process are sharp location-dependent frequency tuning and compressive nonlinearity over a wide stimulus range. The amplifier relies on outer hair cell (OHC)-generated forces driven in part by the endocochlear potential, the ∼+80 mV potential maintained in scala media, generated by the stria vascularis. We transiently eliminated the endocochlear potential in vivo by an intravenous injection of furosemide and measured the vibrations of different layers in the cochlea's organ of Corti using optical coherence tomography. Distortion product otoacoustic emissions were also monitored. After furosemide injection, the vibrations of the basilar membrane lost the best frequency (BF) peak and showed broad tuning similar to a passive cochlea. The intra-organ of Corti vibrations measured in the region of the OHCs lost the BF peak and showed low-pass responses but retained nonlinearity. This strongly suggests that OHC electromotility was operating and being driven by nonlinear OHC current. Thus, although electromotility is presumably necessary to produce a healthy BF peak, the mere presence of electromotility is not sufficient. The BF peak recovered nearly fully within 2 h, along with the recovery of odd-order distortion product otoacoustic emissions. The recovery pattern suggests that physical shifts in operating condition are a critical step in the recovery process.
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Affiliation(s)
- C Elliott Strimbu
- Columbia University Medical Center, Department of Otolaryngology, New York, New York
| | - Yi Wang
- Columbia University, Department of Biomedical Engineering, New York, New York
| | - Elizabeth S Olson
- Columbia University Medical Center, Department of Otolaryngology, New York, New York; Columbia University, Department of Biomedical Engineering, New York, New York.
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Mariano F, Mella A, Vincenti M, Biancone L. Furosemide as a functional marker of acute kidney injury in ICU patients: a new role for an old drug. J Nephrol 2019; 32:883-893. [PMID: 31090022 DOI: 10.1007/s40620-019-00614-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/16/2019] [Indexed: 12/21/2022]
Abstract
New pharmacokinetics insight suggests that the furosemide pharmacology occurring in ICU patients with AKI is similar, but not equal to that described in chronic stable renal patients. Even if the diuretic response to furosemide is expressed by a steep dose-response curve positively correlated with renal function, pharmacodynamic limitations occur when creatinine clearance is < 20 ml/min or urine output is < 500 ml/12 h. In such cases, other factors specifically due to acute tubular injury can interfere with the furosemide-induced diuretic output. As modality of administration recent reports and metanalysis, even if not conclusive, suggest that for the same given dose a continuous infusion of furosemide was superior in diuretic response. For septic shock patients on CVVHDF where treatment adds an additional clearance of furosemide the maximum diuretic response is achieved by a continuous infusion of 20 mg/h of furosemide. At this infusion rate the reached plasma level was < 20 mg/L, a range considered safe and not ototoxic. Therefore, the severity of AKI establishes whether a patient will respond to furosemide. In this review we summarized all these recent updates, also suggesting that the diuretic response under continuous infusion may allow assessing glomerular and tubular functions with increased reliability than a bolus dose. However, validation studies are still needed to support continuous infusion as a stress test.
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Affiliation(s)
- Filippo Mariano
- Nephrology, Dialysis and Transplantation U, Department of Medical Sciences, CTO Hospital, University of Turin, City of Health and Science, Via G. Zuretti 29, 10126, Turin, Italy.
| | - Alberto Mella
- Nephrology, Dialysis and Transplantation U, Department of Medical Sciences, CTO Hospital, University of Turin, City of Health and Science, Via G. Zuretti 29, 10126, Turin, Italy
| | - Marco Vincenti
- Department of Chemistry, University of Turin, Turin, Italy
| | - Luigi Biancone
- Nephrology, Dialysis and Transplantation U, Department of Medical Sciences, CTO Hospital, University of Turin, City of Health and Science, Via G. Zuretti 29, 10126, Turin, Italy
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