9505736 Block This proposal by a young investigator of unusual breadth of expertise spans several levels of biological organization. The basic interest of the PI is in the biology of muscle and, more particularly , how the membrane system within the muscle cells controls the contraction/relaxation cycle of muscles. In ordinary striated muscle, i.e., those that contract to produce movement, these membranes serve as storage depots for calcium ions. The release/sequestration of calcium ions in the membranous system of such muscle cells regulates their contraction. The PI is examining the coupling of these calcium mechanisms to the impulse generated by nerves which initiates the contractile event. To do so she employs a unique muscle cell found in the eye muscles of deep-diving fish such as the marlin, that is, a muscle cell that does not contract but rather produces heat. This "heater tissue" is used to warm blood on its way to the fish's brain, thus keeping the brain warm even while the fish dives in deep and cold water. The PI is currently studying the elaborate counter-current heat exchange system at the base of this heater organ, using biochemical and morphological methodologies to study how these cells regulate the movement of calcium and thereby generate heat. Using a unique, non-contracting muscle system the PI will also be addressing questions of interest to all contractile physiologists.
