Iliac and mesenteric blood flow on release of efferent cervical vagal stimulation
Cevese, A.; Poltronieri, R.; Verlato, G.
Cardiologia 32(7): 667-670
1987
ISSN/ISBN: 0393-1978 PMID: 3690591 Document Number: 300302
The effect of withdrawal of efferent cervical vagal stimulation on mesenteric and iliac blood flows of anesthetized closed chest dogs were investigated with the aim of separating consequences of chronotropic and non-chronotropic mechanisms. The cervical vagus nerves were isolated and sectioned and their peripheral stumps were placed on a couple of bipolar electrodes. Superior mesenteric and left external iliac arteries were isolated and electromagnetic flowmeter probes were implanted. Vagal stimulators were triggered by ECG signals. Experiments consisted in coupled trials, each record started during steady state vagal stimulation. In the first trial stimulators were turned off, while in the second trial stimulation was continued, but the heart was paced in order to suppress the negative chronotropic effect. Arterial blood pressure, right atrial pressure, mesenteric and iliac flows were recorded in floppy disks after A/D conversion through a computerized system. The results indicate an abrupt increase in blood pressure and a fall in right atrial pressure, partly due to non-chronotropic mechanisms and an increase in iliac and mesenteric blood flows. However, iliac resistance decreased but mesenteric resistance was quite stable. This peculiar behavior of the mesenteric vascular bed could result from the onset of a reflex vasodilation concomitant with the withdrawal of a vagally elicited vasodilation, the 2 effects concealing each other.