A cat head model with isolated perfusion by the animal's own blood

Extracorporeal cephalic blood autoperfusion method in the rat. Hemorrheological evaluation and proposed pharmacological uses

We propose a constant cephalic blood perfusion method especially suitable to the rat. Cerebrovascular blood pressure is artificially regulated by an extracorporeal circuit with a perfusion pump and a Starling valve. A hemorrheological evaluation allows one to demonstrate an extracorporeal circuit that shows a growing pathological evolution, which can be purposely accelerated by iterative ischemic episodes. This method can be used (as shown by some examples) as a model for cerebrovascular failure or to study deleterious effects of the extracorporeal circuit.

5-HT antagonism on cerebral and common carotid arteries by the 5-HT uptake inhibitors femoxetine and paroxetine

The 5-hydroxytryptamine (5-HT) antagonism of methysergide was compared with that of the phenylpiperidine 5-HT uptake inhibitors, paroxetine and femoxetine, using two different models; the isolated cat middle cerebral artery and the common carotid artery of pithed rat perfused with the rat's own blood (autoperfusion). The extracorporeal circulation consisted of about 1.5 ml blood, which was temperature regulated to 36-38 degrees at the inlet to the carotid vessel by an automatic thermistor coupled heating system. In these experiments systemic blood pressure responses and perfusion pressure responses to 5-HT were recorded simultaneously. The 5-HT induced contractile response of the middle cerebral artery was reduced in a noncompetitive way by both uptake inhibitors at concentrations above 0.3 microM which is about 100 times the concentration needed for methysergide. In autoperfusion experiments inhibition was observed only at 5 mg/kg of both drugs. However, methysergide 0.001 mg/kg totally abolished all 5-HT responses. The uptake inhibitors can therefore be described as weak 5-HT antagonists.

The effect of variation in perfusion pressure on the capillary blood flow (microflow) in the cerebral cortex of the isolated cat's head preparation

The results of the present experiments show that capillary blood flow in the cerebral cortex fluctuates, whether the cat's head is supplied by the animal's intact circulation or by an artificial circulation system. These variations in blood flow last about 5 to 15 min and range from about 10% below to 10% above the mean. When the perfusion pressure is gradually reduced from 140 mmHg to 60 mmHg, the cortical microflow and the electrical activity of the brain remain almost constant. However, a reduction in perfusion pressure of this magnitude causes a 75% fall in total blood flow through the isolated head.