The combination of hypoxia plus glucose deprivation or of hypoxia plus lactate induces carrier-mediated outward transport of 3H-noradrenaline in the rat vas deferens. Lactate efflux is higher from atria than from vas deferens. Hence, the much lower contribution by outward transport to the spontaneous efflux of 3H-noradrenaline in vas deferens than atria is likely to be due to a better supply of oxygen (and perhaps also glucose) to the 3H-noradrenaline-storing varicosities in vas deferens than in atria.