Gestational changes in mechanical properties of skinned muscle tissues of human myometrium.
We developed a technique to obtain very thin myometrial muscle strips that allowed comparison of characteristic features of contraction from the same strip under intact and membrane-permeable ("skinned") conditions. Absolute tension development per unit of cross-sectional area induced by high potassium and oxytocin concentrations in the intact condition, or by Ca2+ in the skinned condition, markedly increased in human myometrium at term compared with the nonpregnant state. The maximum tension in skinned strips was 8.3 mN/mm2 in nonpregnant strips and 47.5 mN/mm2 at term (both obtained at 10 mumol/L Ca2+). The Ca2+ sensitivity of the contractile proteins in skinned strips also increased at term compared with the nonpregnant state; the half-maximal response of Ca2+ sensitivity was 0.7 mumol/L in the nonpregnant state and 0.3 mumol/L at term. These results suggest that in human myometrium both the amount of contractile proteins and their sensitivity to Ca2+ may increase at term compared with the nonpregnant state.
Izumi
H
H
Department of Obstetrics and Gynecology, School of Medicine, Fukuoka University, Japan.
Ichihara
J
J
Uchiumi
Y
Y
Shirakawa
K
K
D000328:Adult; D002118:Calcium / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D009124:Muscle Proteins / Q000378:metabolism; D009215:Myometrium / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011247:Pregnancy / Q000502:physiology*; D013314:Stress, Mechanical; D014590:Uterine Contraction / Q000502:physiology*
D009124:Muscle Proteins; D010121:Oxytocin; D011188:Potassium; D002118:Calcium