Improved methods for baroreceptor investigations in chronically instrumented rats

We developed a novel approach using inflatable cuffs in order to test the baroreceptor reflex in conscious rats. The cuffs we employed differ from previous approaches in which cuffs are implanted in the thorax. Instead, we placed cuffs around the abdominal aorta and vena cava immediately below the diaphragm. We assessed the utility of this approach in several ways. First, we found that implantation could be accomplished without the stress associated with opening the thoracic cavity. Functioning preparations were far easier to obtain compared to the thoracic approach. The thoracic approach using two-vessel constriction resulted in inordinant mortality and failed preparations. We found that blood pressure changes could be easily exerted over a considerable range in conscious animals with the abdominal cuffs. For instance, blood pressure could be easily manipulated over a range of 100 mmHg (increased or decreased by 50 mmHg from baseline). This simpler and more reliable approach will facilitate baroreceptor investigations in conscious rats.