Stereological analysis of the mitochondrial compartment of the rabbit parotid gland before and after isoprenaline-induced degranulation.

A stereological analysis of the mitochondrial compartment of the rabbit parotid gland has been carried out before and after isoprenaline-induced degranulation. Normally, mitochondria constitute about 5% of acinar cell volume, 6% of intercalcate duct cell volume and 16% of striated duct cell volume. The ratio of inner electron transport membrane to outer limiting membrane is in the range 2.3:1. Two hours after the induction of secretion by isoprenaline a significant (P less than 0.10) increase in the volume fraction of mitochondria in acinar and intercalated duct cells was noted and this may reflect increased oxidative phosphorylation at this time. Other parameters measured suggest that there is some rounding up of mitochondria Another significant feature was an increase in the number of damaged mitochondrial profiles (+80% to +250%, P less than 0.05) after isoprenaline treatment. This finding is discussed in the context of changes in mitochondrial enzyme levels which have been reported in similar situations.