Structural remodeling of the heart and its premotor cardioinhibitory vagal neurons following T(5) spinal cord transection.

Midthoracic spinal cord injury (SCI) is associated with enhanced cardiac sympathetic activity and reduced cardiac parasympathetic activity. The enhanced cardiac sympathetic activity is associated with sympathetic structural plasticity within the stellate ganglia, spinal cord segments T1-T4, and heart. However, changes to cardiac parasympathetic centers rostral to an experimental SCI are relatively unknown.

Dynamic interaction between the heart and its sympathetic innervation following T5 spinal cord transection.

Midthoracic spinal cord injury (SCI) is associated with enhanced sympathetic support of heart rate as well as myocardial damage related to calcium overload. The myocardial damage may elicit an enhanced sympathetic support of contractility to maintain ventricular function. In contrast, the level of inotropic drive may be reduced to match the lower afterload that results from the injury-induced reduction in arterial pressure.

Myocardial ischemia, reperfusion, and infarction in chronically instrumented, intact, conscious, and unrestrained mice.

In the United States alone, the National Heart, Lung, and Blood Institute (NHLBI) has invested several hundred million dollars in pursuit of myocardial infarct-sparing therapies. However, due largely to methodological limitations, this investment has not produced any notable clinical application or cardioprotective therapy. Among the major methodological limitations is the reliance on animal models that do not mimic the clinical situation.

Ventricular function during exercise in mice and rats.

The mouse has many advantages over other experimental models for the molecular investigation of left ventricular (LV) function. Accordingly, there is a keen interest in, as well as an intense need for, a conscious, chronically instrumented, freely moving mouse model for the determination of cardiac function. To address this need, we used a telemetry device for repeated measurements of LV function in conscious mice at rest and during exercise.

How does a hopping kangaroo breathe?

We developed a model to demonstrate how a hopping kangaroo breathes. Interestingly, a kangaroo uses less energy to breathe while hopping than while standing still. This occurs, in part, because rather than using muscle power to move air into and out of the lungs, air is pulled into (inspiration) and pushed out of (expiration) the lungs as the abdominal organs "flop" within the kangaroo's body.