A method for maintaining and protecting chronic arterial and venous catheters in conscious rats

The ability to monitor arterial blood pressure and heart rate directly, as well as to sample venous blood, or inject pharmaceutical agents intravenously is important in pharmacological studies of the cardiovascular system. The rat is a frequently used and accepted animal model for cardiovascular investigations, especially those relating to hypertension. Even though the rat is a major model for these studies, the size of the rat has made it difficult to maintain catheters for a long period of time. Although there have been previous methods available, the authors report on an improved method to implant, maintain, and protect arterial and venous catheters in conscious rats for extended periods of time. A Silastic/Tygon catheter is implanted intraarterially and intravenously, exteriorized, and protected with a spring device. Catheters remained patent throughout a 5-week period during which time direct blood pressure recordings were obtained and baroreflexes were evaluated in conscious, unrestrained rats. The described design and methods provide an inexpensive means to maintain chronically implanted venous and arterial catheters in the conscious rat. Furthermore, rats may be gang housed.