Cardiovascular responses to intracerebroventricular infusion of artificial cerebrospinal fluid in anesthetized strain 13 guinea pigs.
The cardiovascular effects of constant intracerebroventricular infusion in anesthetized strain 13 guinea pigs were studied. Bilateral cerebroventricles of the animals were catheterized stereotaxically with two 20-gauge blunt needles, penetrating 5 to 6 mm into the skull. Baseline cerebroventricular pressure values were 1.3 +/- 0.6 mmHg. After artificial cerebrospinal fluid was infused into the left ventricle at 0.5 ml/h, left cerebroventricular pressure increased to 8.1 +/- 1.6 mmHg (P less than 0.01), while right cerebroventricular pressure reached 5.6 +/- 2.2 mmHg within 20 minutes. No significant changes in mean blood pressure or heart rate were observed. When intracerebroventricular infusion rate increased to 5.0 ml/h, cerebrospinal fluid pressures of left and right cerebroventricles increased to 40.0 +/- 4.8 and 38.4 +/- 4.7 mmHg within 10 minutes from baseline values of 1.5 +/- 0.5 and 1.7 +/- 0.7 mmHg, respectively. Simultaneously, mean blood pressure and heart rate increased from 72 +/- 4 to 101 +/- 9 mmHg and from 195 +/- 11 to 218 +/- 17 beats/min, respectively. However, 30 to 50 minutes later, mean blood pressure, heart rate, and cerebrospinal fluid pressure decreased abruptly, and two of four animals died. We suggest that this technique with a low infusion rate (less than 0.5 ml/h) can be used to deliver certain drugs into the brain ventricles directly without producing undesirable effects on blood pressure or heart rate.
Liu
C T
CT
Department of Clinical and Experimental Physiology, United States Army Medical Research Institute of Infectious Disease, Fort Detrick, Frederick, MD 21702-5011.
Guo
Z M
ZM
D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002555:Cerebrospinal Fluid / Q000502:physiology*; D015170:Cerebrospinal Fluid Pressure / Q000502:physiology*; D004195:Disease Models, Animal; D006168:Guinea Pigs; D006339:Heart Rate / Q000502:physiology*; D007276:Injections, Intraventricular