EFFECT OF AGE ON CONTRACTILITY OF GUINEA-PIG URETER

  • 1 January 1980
    • journal article
    • research article
    • Vol. 17  (6) , 459-461
Abstract
Longitudinal force-length relationships of guinea pig ureter were studied in vitro in animals 3 wk, 3 mo. and 3 yr of age. Distal segments of 3 wk olds underwent a greater percent increase in length in response to an applied resting force than those from older age groups. Resting force-length relations of proximal segments were unaffected by age. Active force was higher in distal segments at all ages and at all lengths. Maximum active force increased with age. The increase in force developed between 3 wk and 3 mo. of age were attributable to an increase in contractility since there was an associated increase in active stress; the increase developed between the 3 mo. and 3 yr olds was associated with increased muscle cross-sectional area but with no change in active stress. No change in contractility appeared to occur during this time interval.