Reversible formation of giant and normal-sized mitochondria in gastric parietal cells of guinea pigs.

ABSTRACT

Mitochondria occasionally increase in size in response to metabolic injury. Numerous studies have reported giant mitochondria in patients with various diseases and animals with metabolic injuries, and there are few reports on giant mitochondria in normal cells under physiological conditions. Here, we report a reversible formation of giant and normal-sized mitochondria in gastric parietal cells of guinea pigs. We morphometrically analyzed the frequency distribution of mitochondrial area on ultrathin sections of parietal cells in guinea pigs fed freely (control group), starved for 60-72 hr (starvation group), and starved and then injected with histamine (histamine group). The distribution was significantly different between the control and starvation group and between the starvation and histamine group the histogram of the starvation group significantly shifted toward large mitochondria compared with that of the control or histamine group; the frequency of mitochondria more than 2 microm2 in size was significantly higher in the starvation group than that in the control or histamine group. This is the first report that clearly demonstrated the presence of giant mitochondria in gastric parietal cells under the starved condition and a mitochondrial recovery in a normal size after the administration of histamine. Because gastric parietal cells change their membrane system according to the state of gastric acid secretion, the present data may offer new insight into the morphological changes in gastric parietal cells.