title: The concentration of ouabain binding sites in biopsies of uterine muscle.
abstract: The concentration of Na, K-ATPase in biopsies of uterine muscle was determined by measurement of [3H]ouabain binding in the presence of vanadate. For this purpose a method previously described for skeletal muscle (Nørgaard et al. 1983) was modified. Biopsies were obtained from uterine muscle from pregnant women (during caesarian section), non-pregnant women (during hysterectomy) and from adult, non-pregnant guinea-pigs and rats. The ouabain binding site concentration in uterine muscle of the pregnant women averaged 72 +/- 2 pmol g-1 wet wt (n = 8), with an apparent dissociation constant (KD) for ouabain of 3 x 10(-9) mol l-1. The ouabain-binding capacity in uterine muscle of the non-pregnant women amounted to 83 +/- 9 pmol g-1 wet wt (n = 8). In uterine muscle of the guinea-pig, two populations of ouabain binding sites were observed: one with a maximum binding capacity of 230 pmol g-1 wet wt and an apparent KD of 1.6 x 10(-6) mol l-1, and one with a maximum capacity of 62 pmol g-1 wet wt and an apparent KD of 5 x 10(-8) mol l-1. Immediate freezing of the biopsies in liquid N2 and storage at -60 degrees C for up to 6 weeks caused no change in ouabain-binding capacity. The dry weight/wet weight ratio of the samples from different subjects showed values of around 20%. It is concluded that the concentration of Na-K pumps in human uterine muscle can be quantified by [3H]ouabain binding using samples weighing 5-10 mg.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute of Physiology, University of Aarhus, Denmark.
authors.forename: M E
authors.initials: ME
authors.lastname: Everts
authors.forename: K
authors.initials: K
authors.lastname: Skajaa
authors.forename: K
authors.initials: K
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000818:Animals; D001665:Binding Sites; D005260:Female; D005615:Freezing; D006168:Guinea Pigs; D006801:Humans; D008875:Middle Aged; D010042:Ouabain / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism; D011247:Pregnancy / Q000378:metabolism*; D051381:Rats; D015222:Sodium Channels / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013395:Sucrose / Q000494:pharmacology; D014599:Uterus / Q000378:metabolism*
chemical_list: D015221:Potassium Channels; D015222:Sodium Channels; D013395:Sucrose; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase