Many biological functions—such as nerve impulses, muscle contraction, vision and even conception—have their basis in a sudden change in cell membrane permeability. Specific membrane proteins act as gates or agents of active transport, regulating the flow of molecules and ions between the cell and its environment. Members of one class of membrane proteins, the ion channels, open in response to electrical, chemical or mechanical stimuli to allow the spontaneous flow of ions down a concentration or potential gradient across the cell membrane. In 1976 Erwin Neher and Bert Sakmann reported using a tiny yet simple electrode, called a patch clamp electrode, pressed up against a frog muscle cell to record for the first time the opening and closing of a single ion channel1 in a biological membrane. For their invention, refinement and application of the patch clamp and of the electronics for recording the minute currents it samples, Neher and Sakmann, now at the Max Planck Institutes in Göttingen and Heidelberg, respectively, have been awarded the 1991 Nobel Prize in Physiology or Medicine. In honoring the two, the Nobel Assembly at the Karolinska Institute cited “their discoveries concerning the function of single ion channels in cells.”

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