  Properties of fluctuations in two chains of Tomonaga-Luttinger liquids
coupled by the interchain hopping have been studied by calculating retarded
response functions $\chi^R_{\rho} (q_x,q_y;\omega)$ for charge and $\chi^R_{\p}
(q_x,q_y;\omega)$ for spin where $q_x$ and $q_y (=0$ or $\pi$) denote the
longitudinal and transverse wave vector, respectively, and $\omega$ is the
frequency. We have found the notable fact that the repulsive intrachain
interaction results in the clear enhancement of ${\rm{Im}}\chi^R_\p
(q_x,\pi;\omega)$ and the suppression of ${\rm{Im}}\chi^R_\rho
(q_x,\pi;\omega)$ at low energies. This result indicates the importance of the
dynamical effect by the spin fluctuation with $q_y = \pi$ and small $\omega$,
which has a possibility to give rise to the attractive interaction for the
electron pairing.
