| Two-dimensional acoustic impedance imaging is useful for observation of living organs without invasion. In order to visualize the distribution of specific functional proteins in the cerebellar cortex, we proposed direct or complex-including heavy metal treatment to elevate the acoustic impedance of a particular cerebellar layer. Heavy metal binding was useful for acoustic impedance imaging; however, metal binding to a protein molecule was not always specific. To observe the distribution of specific molecules, we constructed p-cymene ruthenium (Ru)-binding peptides, namely calciseptine, a competitive L-type calcium channel blocking peptide, and ω-agatoxin IVA, a P-type channel blocker. P-cymene Ru binds to the amino group of each peptide without impairment of pharmacological function, so we could observe the characterized area by p-cymene Ru-binding peptide treatment. Each peptide-Ru complex increased the impedance of the cerebellar cortex corresponding to the developmental molecular distribution. We suggest that a metal-binding competitive reagent would be useful for living organ observation, especially using an acoustic impedance microscope. |