Morphological changes in the rat carotid body following acute sodium nitrite treatment

• A single injection of sodium nitrite causes the development of marked morphological changes in the rat CB.
• The structural alterations are characterized by a prominent increase in the CB size with vascular expansion.
• The observed CB enlargement is statistically significant compared to normoxic controls.
• The rat CB morphology following acute sodium nitrite treatment is similar to that observed in chronic hypoxia.

The carotid body (CB) is a small neural crest-derived chemosensory organ that detects the chemical composition of the arterial blood and responds to its changes by regulating breathing. The effects of acute nitrite treatment on the CB morphology in rats were examined by morphometry. We found that 1 h after administrating a single dose of sodium nitrite, the CB underwent structural changes characterized by a prominent increase in its size with a marked, several-fold dilation of the blood vessels. The obvious CB enlargement mostly due to apparent vasodilation and glomus cell hypertrophy was at its highest one day later and persisted until the fifth day. 20 days after the treatment, the CB regained its size to the normoxic control state. Morphometric analysis revealed that the CB size increase in treated animals is statistically significant when compared to that of untreated controls. It can be inferred that the nitrite-exposed CB displays remarkable structural plasticity and enlarges its size mostly through vascular expansion.