The concentration of ouabain binding sites in biopsies of uterine muscle

TY - JOUR

T1 - The concentration of ouabain binding sites in biopsies of uterine muscle

AU - Everts, M. E.

AU - Skajaa, K.

AU - Hansen, K.

PY - 1990/1/1

Y1 - 1990/1/1

N2 - The concentration of Na,K-ATPase in biopsies of uterine muscle was determined by measurement of [3H]ouabain binding in the presence or vanadate. For this purpose a method previously described for skeletal muscle (Norgaard 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 (K(D)) 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 K(D) 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 K(D) of 5 x 10-8 mol l-1. Immediate freezing of the biopsies in liquid N2 and storage at -60°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. The method may provide a useful approach in clinical studies, i.e. analysis of the changes in Na, K-ATPase concentration that may occur as a basis for disturbances of labour.

AB - The concentration of Na,K-ATPase in biopsies of uterine muscle was determined by measurement of [3H]ouabain binding in the presence or vanadate. For this purpose a method previously described for skeletal muscle (Norgaard 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 (K(D)) 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 K(D) 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 K(D) of 5 x 10-8 mol l-1. Immediate freezing of the biopsies in liquid N2 and storage at -60°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. The method may provide a useful approach in clinical studies, i.e. analysis of the changes in Na, K-ATPase concentration that may occur as a basis for disturbances of labour.

KW - guinea-pig

KW - human

KW - Na,K-ATPase

KW - pregnancy

KW - rat

KW - uterine muscle

KW - [H]ouabain

UR - http://www.scopus.com/inward/record.url?scp=0025142589&partnerID=8YFLogxK

U2 - 10.1111/j.1748-1716.1990.tb08952.x

DO - 10.1111/j.1748-1716.1990.tb08952.x

M3 - Journal article

C2 - 2173352

AN - SCOPUS:0025142589

SN - 0001-6772

VL - 139

SP - 503

EP - 510

JO - Acta Physiologica Scandinavica

JF - Acta Physiologica Scandinavica

IS - 3

ER -