The relation of axonal transport of mitochondria with microtubules and other axoplasmic organelles

Abstract

Axonal transport of mitochondria was studied in frog sciatic nerves incubated in agents selected for their known or alleged effect on microtubules or axonal flow. Quantitative data on mitochondria, microtubules, neurofilaments, endoplasmic reticulum, and cross-sectional area of the axon indicate that axonal transport of mitochondria is dependent on microtubules. When more than half of the microtubules are destroyed, the axonal transport of mitochondria is diminished in proportion to the destruction of microtubules. Axonal transport of mitochondria is not related to neurofilaments and endoplasmic reticulum. Changes in the cross-sectional area of axons, even upon reduction to half the normal size, do not noticeably affect mitochondrial transport. Cyanide which blocks oxidative metabolism also blocks axonal transport of mitochondria, but analysis of fine structure indicates that cyanide is destructive to microtubules as well.