A novel knot method for individually measurable aortic constriction in rats.

A novel knot method in rats is reported that addresses several drawbacks in the current model of aortic constriction-induced heart hypertrophy. Using a rat model, we developed a two-step procedure that includes 1) measurement of individual aorta circumference using a surgical thread; and 2) constriction of the aorta using a thread with the desired length predefined by a knot at each end for a measurable reduction of the aortic circumference as referenced to the measurement in step 1. This knot approach produces a manageable gradient of aortic constriction in each rat, reaching a consistency among experimental animals that cannot be achieved by the traditional needle method. Notably, the animal model produced by our knot method showed cardiac hypertrophy and dysfunction with the severity proportional to the percentage reduction of the aorta circumference (50% vs. 60%). Additionally, our new procedure produced a lower mortality rate compared with the traditional needle method. Therefore, we recommend this knot method as an alternative procedure for aortic constriction with desired gradient in rats and larger-animal models.