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. Author manuscript; available in PMC: 2010 May 1.
Published in final edited form as: Hypertension. 2009 Mar 16;53(5):867–876. doi: 10.1161/HYPERTENSIONAHA.108.128264

Figure 2.

Figure 2

GC-C-stimulating activities of commercially-obtained huUgnA and huUgnB. (a) Each data point represents the mean value (± SEM) for 9 experiments with huUgnA (filled symbols) and 3 experiments with huUgnB (open symbols). The curves are fit with the log (agonist) vs dose equation (see the Methods), using an EC50 of 1.8 × 10−7 M for huUgnA and an EC50 of 1.5 × 10−5 M for huUgnB. Responses to peptides were significantly different from control (p < 0.05 or lower by 2 way ANOVA) at all doses of huUgnA greater than 2.5 × 10−9 M, and all doses of huUgnB greater than 8 × 10−9 M. huUgnA responses were greater than huUgnB at all doses above 8 × 10−9 (p<0.01 or less) (b) The stimulatory effect of huUgnA on T84 cells is not antagonized by a 7-fold excess of huUgnB. The bars show (from left to right) the cyclic GMP levels in cells treated with control medium, with 25 nM huUgnA, with 180 nM huUgnB, or with a combination of the two peptides (mean ± SEM, n = 3). (c) The A and B isomers (filled and open circles, respectively) interconvert slowly in vitro. Samples were incubated at 50° C in 1 mM citrate buffer (pH 4), then diluted into bioassay medium. The pH was adjusted to 7.0, and activity was measured in the T84 cell bioassay. T84 responses to both isomers at 48 hr were significantly different from time zero (p < 0.01, two-way ANOVA), but were not different from each other.