Email

brownell@bcm.edu

Positions

Jake and Nina Kamin Chair of Otorhinolaryngology and Communicative Sciences

Baylor College of Medicine
Houston, Texas US

Professor

Otolaryngology-Head & Neck Surgery
Baylor College of Medicine
Houston, TX US

Education

Ph.D. from University Of Chicago

01/1973 - Chicago, IL United States

Physiology

S.B. from University Of Chicago

01/1968 - Chicago, IL United States

Physics

Professional Interests

• Research Interests

Professional Statement

The remarkable sensitivity of mammalian hearing results from the ability of inner ear sensory receptor cells (called outer hair cells) to generate mechanical force in response to small electric fields. These forces can follow electrical signals up to 100 kHz and cause cell length changes that are easily seen when the cell is isolated from the cochlea. The mechanism responsible for this electromotility is a membrance based motor that resides in the cell's lateral wall. The lateral wall is a composite structure with nanoscale dimensions. Three layers are found within 100 nm of the cell's surface:

The plasma membrane
A highly organized cortical lattice made up of cytoskeletal proteins
A novel subcellular organelle called the subsurface cisterna
This trilaminate organization is unique to the outer hair cell as is electromotility. We have developed techniques to selectively label and functionally dissect the layers. The nature of lipid-protein interactions in the two membranous layers is of particular interest. The contribution of each layer to the cell's electrical and mechanical anatomy is measured and computational models developed.

Outer hair cells are investigated in vitro and subjected to a variety of mechanical, electrical, and chemical stimuli. Video-enhanced, confocal-laser-scanning, and atomic-force microscopy and optical tweezers are used to measure lateral diffusion in membranes, cell movements ionic currents, and membrane electromechanics. Intracellular microelectrodes, patch clamp techniques, suction electrodes, and voltage- and ligand- sensitive dyes are used to investigate the electroanatomy of cells including the ion channels found in the cell's different membrane domains. Analytic and numerical models are used to analyze mophometric data, extract elastic moduli of the different cell structures, and clarify ionic and molecular pathways within the cell.

Websites