Microwave Irradiation of Cryostat Sections Accelerates and Improves
Nitric Oxide Synthase Staining,
Forte, Michele and Gu, Jiang, Cell Vision_,
Vol. 1, No. 1, 1994.
A recent increase in nitric oxide synthase research demands a sensitive
and reliable morphological detection of its enzyme, nitric acid synthase
(NOS). As an antibody against NOS is not readily available, a widely
used histochemical stain for NADPH specifically depicts the distribution
of NOS in paraformaldehyde-fixed frozen sections. We found that irradiating
the crysostat section in a microwave oven significantly improved
the detection sensitivity of this method. Various power settings
and durations of microwave irradiation were tested with a domestic
oven utilizing cryostat sections of paraformaldehyde fixed rat brain
and heart as models. NADPH specifically stained cytoplasm of neurons,
nerve terminals, endothelial cells and vascular smooth muscle cells.
Microwave treatment at high power setting (600 W) significantly increased
the staining abundance and density while lowering the background.
In particular, many more small diameter nerve fibers were visualized
in comparison with the conventional procedure. Microwave irradiation
shortened the drying period of the cryostat sections from 30 min
to 1 hr to about 10 min and enhanced the tissue section attachment.
Cell morphology appeared to improve. The beneficial effects of microwave
irradiation might be due to the unmasking of NADPH molecules, activation
of enzyme activities, minimizing the loss of activity by shortening
the drying time or a combination of the above. We conclude that microwave
irradiation of cryosections significantly improves the efficiency
of NOS staining.