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Functional studies have yet to be undertaken to establish which brain region subserves the parasympathetic regulation of the cerebral circulation. Using 31 anesthetized rats with precluded cervical sympathetic trunks, we therefore attempted to perform chemical stimulation of the greater petrosal nerve (GPN) cell group, which is a subgroup of the superior salivatory nucleus and sends off axons largely to the parasympathetic pterygopalatine ganglion via the GPN component of the facial nerve. The cerebrocortical blood flow was monitored with a laser-Doppler flowmeter. Unilateral stimulation of the GPN cell group by microinjection of L-glutamate reduced the ipsilateral cerebrocortical vascular resistance, maximally by 16.4 +/- 4.1% (mean +/- SD, n = 61). The response was not mediated by the classic muscarinic receptors of the cerebral vessel wall. However, pharmacological blockade of the peripheral parasympathetic ganglia and acute and chronic bilateral removal of the parasympathetic postganglionic fibers originating in the pterygopalatine ganglion abolished the response. The present data thus provide functional evidence that the GPN cell group may constitute a parasympathetic cerebrovasodilator center.

The effects of electrical stimulation of the pressor area of the fastigial nucleus (FN) of cerebellum on regional cerebral blood flow (CBF) were examined in anesthetized, paralyzed rats. CBF was measured in tissue homogenates by the Kety principle using 14C-iodoantipyrine as an indicator during FN stimulation, during stimulation of the vermal cortex, or after placement of electrodes in FN (unstimulated controls). Blood gases and systemic arterial pressures were comparable in the three groups. FN stimulation elicited a widespread and significant (P less than 0.005) increase in CBF in 12 of 13 areas. Flow was maximally increased in cerebral cortex (up to 220% of control) but also rose in selected regions of telencephalon, diencephalon, mesencephalon, lower brain stem, and in white matter of the corpus callosum (172%). Flow was not increased in cerebellum. The increase in CBF persisted after transection of the spinal cord at C1 or cervical sympathectomy. In five rats, hypercarbia (PCO2 to 63 mmHg) increased CBF in all 13 regions but in a pattern differing from FN stimulation. Excitation of neurons originating in, projecting to, or passing through FN can elicit a potent and virtually global increase of CBF. The effect appears mediated by intrinsic pathways of the central nervous system.

Background-We developed a total right ventricular (RV) exclusion procedure for the treatment of isolated congestive RV failure. The objective of the present study was to elucidate the effects of a complete removal of RV volume overload (RVVO) on the surgically created single left ventricle (LV). Methods and Results-Three adults (2 arrhythmogenic RV dysplasia, 1 Ebstein) and 5 children (all Ebstein) in NYHA class IV underwent the procedure. The RV free wall was resected from the heart, and the tricuspid orifice was closed. Pulmonary blood supply was obtained by a cavopulmonary connection in 6 patients and a systemic-pulmonary shunt in 2. The LV function was evaluated by 2-dimensional echocardiography 1 month after the surgery. All patients are alive. The paradoxical movement of the interventricular septum and geometry of the LV expressed by its eccentricity (2.

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