Table 1.

Models of Huntington’s disease discussed in this paper.

HD cell or mouse model	Origin or genetic construct	Effects on oxidative metabolism and mitochondrial Ca2+ handling
Conditionally immortalized, mutant STHdhQ111/Q111 striatal neuronal progenitor cells [20]	Derived from knock-in mice with 111 CAG repeats in endogenous htt gene	Inhibited respiration, but respiratory Complexes are not affected [23] Slightly reduced maximal respiratory rate, no difference in basal respiration [25] Deficient OXPHOS and decreased Complex I and IV activities [26] Reduced Ca2+ uptake capacity and increased propensity to PTP induction in mitochondria isolated from STHdhQ111/Q111 cells [59,60]
Transgenic R6/2 mice [72]	N-terminal fragment of human htt with 115-150 or 195 CAG repeats	Activities of Complex IV and aconitase are decreased [27] Respiratory impairment of striatal mitochondria [31] Respiration of synaptic and nonsynaptic mitochondria is not affected [34] Oxygen consumption is not affected in 8 week old mice, but increased in 14- week-old animals [43] Increased propensity to Ca2+ -induced PTP induction in skeletal muscle mitochondria [61] Augmented Ca2+ uptake capacity in brain nonsynaptic mitochondria [39]
Transgenic N171-82Q mice [73]	N-terminal fragment of human htt with 82 CAG repeats	Decreased Complex IV activity [28] Activities of Complexes I-IV are not decreased, glycolysis is increased [37] ADP-stimulated respiration of isolated brain mitochondria is decreased [30] Oxygen consumption by whole animals slightly increased, electron respiratory chain is not compromised [42]
Transgenic D9-N171- 98Q mice, also known as DE5 mice [74]	N-terminal fragment of human htt with 98 CAG repeats	Decreased respiration of succinate- fueled striatal mitochondria; Complexes I and IV as well as ATP synthase are not affected [29]
Transgenic HD48 and HD89 mice [38]	Full-length human htt gene with 48 or 89 CAG repeats	Complexes I-IV are not affected in the striatum and cortex [38]
Transgenic YAC72 mice [75]	Full-length human htt gene with 72 CAG repeats	Diminished mitochondrial membrane potential, decreased Ca2+ uptake capacity [14]
Transgenic YAC128 mice [76]	Full-length human htt gene with 128 CAG repeats	Augmented mitochondrial depolarization in response to Ca2+ in medium spiny neurons, increased susceptibility to PTP induction [63] Augmented Ca2+ uptake capacity in brain nonsynaptic mitochondria [39]
Transgenic BACHD mice [77]	Full-length human htt gene with 97 mixed CAA-CAG repeats	No effect of mHtt on oxidative metabolism in cultured astrocytes and neurons [41]
Knock-in Q50, Q92, and Q111 mice [78]	Mouse htt gene with inserted 50, 92, or 111 CAG repeats in exon 1	No increase in sensitivity to Ca2+- induced damage in striatal and cortical nonsynaptic mitochondria [65]
Knock-in Hdh150Q mice [79]	Mouse htt gene with inserted 150 CAG repeats in exon 1 in a single allele (Hdh150/+) or both alleles (Hdh150/150)	Respiration of striatal cultured neurons from Hdh150/+ is not affected [39] Liver mitochondria from Hdh150/150 mice have increased propensity to Ca2+ -induced PTP [32]. No change in Ca2+ uptake capacity in brain nonsynaptic mitochondria [39]
Transgenic BACHD rats [80]	Full-length human htt gene with 97 mixed CAA/CAG repeats	No difference in respiration of cultured striatal neurons incubated with high glucose and pyruvate; modest decrease in maximal respiration in the presence of low glucose; respiration of cortical neurons is not affected [40]
Transgenic HD rats [81]	Express 727 amino acids of the htt51Q gene, corresponding to 22% of the full-length gene	Reduced mitochondrial membrane potential stability in response to Ca2+, decreased Ca2+ uptake capacity, increased propensity to PTP induction [62]