TABLE 2

The weighted mean, coefficient of variation, and geometric mean of total membrane protein abundance of drug transporters in the proximal jejunum (jejunum I) obtained from the meta-analysis of measurements in tissue of healthy Caucasian adults

TransporterMeanaCVGeometric MeanaNumber of SamplesNumber of StudiesHeterogeneityReference
PYes/No
%
ABCB1 (P-gp)0.4440.371130.98NoGröer et al. (2013), Oswald et al. (2013), Drozdzik et al. (2014)
ABCC2 (MRP2)0.86680.711130.82NoGröer et al. (2013), Oswald et al. (2013), Drozdzik et al. (2014)
ABCC3 (MRP3)0.58640.4972N/AbN/AbGröer et al. (2013), Drozdzik et al. (2014)
ABCG2 (BCRP)0.34620.291130.93NoGröer et al. (2013), Oswald et al. (2013), Drozdzik et al. (2014)
SLC10A2 (ASBT/IBAT)0.0143c0.0161N/AbN/AbDrozdzik et al. (2014)
SLC15A1 (PepT1)3.69413.411130.92N/AbGröer et al. (2013), Oswald et al. (2013), Drozdzik et al. (2014)
SLCO2B1 (OATP2B1)0.4740.321130.57NoGröer et al. (2013), Oswald et al. (2013), Drozdzik et al. (2014)
SLC22A1 (OCT1)0.65490.5861N/AbN/AbDrozdzik et al. (2014)
SLC22A3 (OCT3)0.06740.0561N/AbN/AbDrozdzik et al. (2014)
SLC51A/B (OST-α/β)0.47d99d0.4711N/AbN/AbHarwood (2015)
• ASBT, apical sodium-dependent bile acid transporter; BCRP, breast cancer resistance protein; N/A, not applicable; PepT1, peptide transporter 1.

• a Values are given as picomoles per milligram of total membrane protein.

• b Heterogeneity reporting is not applicable with only one or two studies, when considering subtracting the degree of freedom component (i.e., n minus one study).

• c The final CV value for jejunum I SLC10A2 was taken from Hilgendorf et al. (2007), based on jejunum mRNA data since it was determined that low abundance levels could give rise to inflated interindividual variability due to analytical imprecision at such low levels of expression.

• d For OST-α/β, the mean abundance is from a distal jejunum sample and is based on the α-subunit data considering the rate-limiting component for conferring OST-α/β activity (Sun et al., 2007). Also, only a single sample was available; therefore, the CV value was obtained from a combined analysis of jejunum samples from relative and absolute data.