Is Aortic Impedance Altered in Dwarf Mice?

Dwarf mouse (deficient in growth hormone and insulin-like growth factor-1) lives about 30% longer than wild type mice. However, very little is known about their cardiovascular physiology. We examined the aortic input impedance in dwarf mice and their wild-type littermates to evaluate any differences. Aortic impedance was determined using pressure and velocity signals which are independent of body size. Significant differences were observed in the body weight, aortic systolic, diastolic and mean pressures, and peak and mean aortic flow velocities. No differences were observed in impedance parameters of peripheral resistance, impedance at first harmonic, and characteristic impedance between the two groups. However, the impedance curve in the dwarf mice was higher at low frequency and decreased gradually with increasing frequencies but in the wild type mice the impedance curve oscillated around the characteristic impedance.