Nociceptive neurons play an important role in ischemia by sensing and transmitting information to the CNS and by secreting peptides and nitric oxide which can have local effects. Whilst these responses are probably primarily mediated by acid sensing channels other events occurring in ischemia may also influence neuron function. In this study we have investigated the effects of anoxia and anoxic aglycaemia on Ca²⁺ regulation in sensory neurons from rat dorsal root ganglia. Anoxia increased [Ca²⁺]_i by evoking Ca²⁺ release from two distinct internal stores one sensitive to FCCP and one sensitive to caffeine, CPA and ryanodine (assumed to be the endoplasmic reticulum (ER)). Anoxia also promoted progressive decline in ER Ca²⁺ content. Despite partially depolarising mitochondria, anoxia had relatively little effect upon mitochondrial Ca²⁺ uptake when neurons were depolarised but substantively delayed mitochondrial Ca²⁺ release and subsequent Ca²⁺ clearance from the cytosol upon repolarisation. Anoxia also reduced both SERCA activity and Ca²⁺ extrusion (probably via PMCA). Thus anoxia has multiple effects upon [Ca²⁺]_i homeostasis in sensory neurons involving internal stores, mitochondrial buffering, and Ca²⁺ pumps. Under conditions of anoxic aglycaemia there was a biphasic and more profound elevation of [Ca²⁺]_i which was associated with complete ER Ca²⁺ store emptying and progressive, and eventually complete, inhibition of Ca²⁺ clearance by PMCA and SERCA. These data clearly show that loss of oxygen, and exhaustion of glycolytic substrates, can profoundly affect many aspects of cell Ca²⁺ regulation and this may play an important role in modulating neuronal responses to ischemia.