Cardiac function in young and old Little mice.

Area of Science:

• Cardiovascular Physiology
• Gerontology
• Genetics of Aging

Background:

• Longer-living mouse models are crucial for understanding aging mechanisms.
• Cardiac function declines with age, impacting overall health and longevity.
• The relationship between cardiac reserves and longevity is not fully understood.

Purpose of the Study:

• To investigate cardiac function and stress response in young and old Little mice compared to wild-type (WT) mice.
• To determine if enhanced cardiac reserves contribute to the longevity observed in Little mice.
• To assess age-related changes in cardiac performance and stress tolerance.

Main Methods:

• Echocardiography and left ventricular pressure (P) measurements were used.
• Cardiac flow velocities, dimensions, and pressure derivatives (+dP/dt(max), -dP/dt(max)) were analyzed.
• Dobutamine stress tests were performed to evaluate cardiac response to pharmacological stress.

Main Results:

• Young Little mice exhibited lower resting cardiac function (velocities, LV dimensions, +dP/dt(max), -dP/dt(max)) than young WT mice.
• Fractional shortening (FS) increased with age in Little mice, and +dP/dt(max)/-dP/dt(max) did not decline.
• Old WT mice showed decreased +dP/dt(max)/-dP/dt(max) with age, while Little mice maintained their dobutamine stress response.
• Old Little mice had decreased velocity indices compared to old WT mice, but other parameters were similar.

Conclusions:

• Resting cardiac function in Little mice is lower at a young age but remains stable with aging.
• Cardiac function in response to stress is preserved with age in Little mice, contrasting with WT mice.
• Enhanced cardiac reserves may not be a universal characteristic of all mouse models exhibiting increased longevity.