  For a sample of 25 dwarf irregular galaxies with distances D < 5 Mpc and
measured oxygen abundances, we present results derived from stellar masses and
galaxy luminosities from near-infrared imaging with IRAC on the Spitzer Space
Telescope. We have constructed the appropriate luminosity-metallicity (L-Z) and
mass-metallicity (M-Z) relations, and compared these relations with their
corresponding relations from the Sloan Digital Sky Survey (SDSS). We obtain the
following results. 1. The dispersion in the near-infrared L-Z relation is
reduced with respect to the dispersion in the optical L-Z relation, which
agrees with expectations for reduced variations of stellar mass-to-light ratios
at longer wavelengths compared to optical wavelengths. 2. The dispersion in the
optical L-Z relation is similar over approximately 11 mag in optical
luminosity. 3. With our constructed M-Z relation, we have extended the SDSS M-Z
relation to lower masses by about 2.5 dex in stellar mass. 4. The dispersion in
the M-Z relation appears to be comparable over a range of 5.5 dex in stellar
mass.
