Expression of 132 bp and 87 bp variant mRNAs of the Maxi-K α subunit. The histograms show the mean (± standard error of the mean, SEM) of the ratios of spliced exon to total maxi-K α subunit mRNA for both (A) the 87 bp and (B) the 132 bp variants in NP, PNL and PL tissues. Results indicate significantly higher expression of the 132 bp exon as a proportion of the total α subunit with labour onset, compared to non-pregnant and pregnant not-in-labour samples. There is no change in expression of the 87 bp variant between the three tissue sets. Tissue sets are indicated by striped columns (non-pregnant, NP), black columns (pregnant not-in-labour, PNL) and open columns (pregnant in-labour, PL). *P < 0.05 versus PL; +P < 0.01 versus PL.