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Acker H, Eyzaguirre C, Goldman WF: Redox changes in the mouse carotid body during hypoxia. . Brain Res. 1985 Mar 18;330(1):158-63.
The carotid body of the mouse is ideally suited for in vitro photometric and fluorometric studies using transillumination. It is small, thin and translucent. Photometric recordings were made by using a dual wavelength method. Wavelengths of 550 nm (maximal absorbance, MA) and 540 nm (isosbestic point, IP) were employed to study cytochrome c, 600 nm (MA) and 620 nm (IP) for a pigment presumed to be cytochrome aa3, 580 nm (MA) and 570 or 542 nm (IP) to control for possible effects of hemoglobin (Hb). Exposure of the organ to NaCN (10-50 nM) reduced cytochromes c and putative aa3. Hypoxia (produced by superfusing with a medium equilibrated with 100% N2) reduced cytochrome c but tended to oxidize the presumed cytochrome aa3. These effects were apparent at a medium pO2 of 100 torr or less. Fluorometry revealed reduction of NADH under both cyanide exposure and hypoxia. There was little or no interference by Hb when the preparations were carefully washed of remaining red cells. The precise site of the recorded mitochondria is unknown: they could have been located in the parenchymal cells (type I and/or II), nerve terminals, smooth muscle fibers, etc. Resolution of this point will need using dissociated carotid body cells. Further, the possible presence of a special respiratory pigment responding at a wavelength similar to that exciting cytochrome aa3 has not been discarded. Its study would require isolating carotid body mitochondria. |
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