Table 4. Predicted cellular maintenance energy and alternative respiration ratio according to the type of operating acceptor for the translocated reducing equivalents when a Glycerol-P shuttle mechanism was considered.

Assumptions

Calculated Values

Shuttle Reducing
Mechanism Form Generated

I ^(b)

Yes

NADH₂(c)è NADH₂ (m)

1.83

93

II ^{(c )}

Yes

NADH₂(c)è FADH₂ (m)

3.66

70

^(a) Evaluated as R17/(R15+ R16 +R17).

^(b) Settings: R15=0; R16=(1/3)R13; R17=(1/3)(R2+R10+R12)+ R13; R24 = (1/3)R2. Mitochondrial NAD⁺ is assumed as the Glycerol-P shuttle acceptor. Hence, mitochondrial FADH would be provided by the Krebs cycle (R13) while all the mitochondrial NADH generated must be consumed by the alternative respiration (R17). The NADH(m) pool would be made up by the contributions from Krebs cycle (R13), mitochondrial citrate excretion (R12), glycerol shuttle operation (R10) and (R24).

^(c) Settings: R15=0; R16=(1/3)(R2+R13+R10); R17=R13+(1/3)R12; R24=(1/3)R2. Mitochondrial FAD⁺ is assumed as the Glycerol-P shuttle acceptor. Hence, the FADH generated would represent the contribution of reduction equivalents translocated through the glycerol shuttle (R24 and R10) as well as the ones produced at the Krebs Cycle (R13). The rate of the alternative respiratory system (R17) should collect all the mitochondrial NADH₂ produced [Krebs cycle (R13) plus citrate synthesis (R12)].