Influence of mechanical stretch on growth and protein turnover of rat uterus.

A new technique has been developed and used to distend the uterus of nonpregnant rats for up to 5 days. Continuous distension of the saline-filled uterus induced rapid and extensive growth of the whole uterus and the myometrium by a combination of hyperplasia and hypertrophy. In both cases, 1 day after this imposition of mechanical stretch significant increases (25-50%) in the protein, RNA, and DNA contents were found, with larger changes (100-250%) being progressively expressed up to 5 days. This stretch-induced growth primarily results from a stimulation of protein synthesis (measured both in vivo and in vitro), with little or no change being evident in the rate of protein breakdown. These findings have been discussed in relation to the role of stretch in the growth of the uterus during pregnancy and stretch-induced responses found in other types of muscle.

Impairment of flow in routine gravity-fed intravenous infusions to surgical patients.

1. Gravity-fed intravenous infusions were studied in patients by using continuous flow recording and a new resistance-measuring method. 2. A common, though preventable, cause of reduced flow was the gradual deformation of the plastic tubing under the regulator clamp. 3. In many cases there was some constriction of the cannulated vein and in a few this constriction was severe enough to seriously impair the infusion. The severity of the constriction varied periodically. 4. There was no evidence of troble due to a generally raised pressure in the arm veins nor was clotting in the cannula a serious problem. 5. A simple test is described which may be found useful clinically for assessing the difficult infusion.