  Nuclear magnetic relaxation rate 1/T_1 in iron-pnictide superconductors is
calculated using the gap function obtained in a microscopic calculation. Based
on the obtained results, we discuss the issues such as the rapid decrease of
1/T_1 just below the transition temperature and the difference between nodeless
and nodal s-wave gap functions. We also investigate the effect of Coulomb
interaction on 1/T_1 in the random phase approximation and show its importance
in interpreting the experimental results.
