Sensing Kinetics of Umami Receptor in Rats Intestinal Mucosa

Umami receptors existed not only in taste tissues,but also in intestinal mucosa and other tissues. In this study,SD rats as research meterials,the sensor was prepared by immobilizing intestinal mucosal tissue to sence the representative umami substances:Sodium glutamate,disodium inosinate,disodium guanylate. The results showed that,the umami recepter and the ligand exhibited a hyperbolic kinetic features similar to enzyme-substrates. The Line weaver-Burk plot method was used to calculate umami substances and receptors activation constants,which were K_a=1.136×10^-13 mol/,K_b=1.443×10^-13 mol/L,K_c=2.080×10^-13 mol/L,respectively. The sensitivity of intestinal mucosal tissue to these three kinds of umami was summarized as follows:Sodium glutamate,disodium inosinate,disodium guanylate. The average number of intestinal mucosa receptors was calculated as:2.30,2.89,4.16/cell. It indicated that the lower of K,the more active the activation cell was,the more sensitive the signal was,the fewer receptors on average per cell when the receptor ligand was saturated. The cell signal amplification factors were N₁=1.9055×10⁴,N₂=1.6642×10⁴,N₃=6.0799×10³,respectively. The results and the resulting active constant and the average number of receptors on cells,and the signal output generated by ligand and receptor efficiency was higher,the signal magnification. In summary,in intestinal mucosa,the sensor could quantitatively describe the ligand-receptor action(receptors activation constants),receptor number and cell signal amplification factors,the kinetic parameters could provide an evaluation method and scientific basis for evaluating the sensing activity and the physiological function of various receptors in the intestinal mucosal system.