Vagal cardioinhibitory area in and around the caudal inferior olivary nucleus of cats. I. Localization and connection.
Bradycardia was produced by electrical stimulation and injection of glutamate (200 nl, 1 M) to the regions in and around the extremely caudal parts of the inferior olivary nucleus (ION) in chloralose-urethane anesthetized cats. Either medullary transection at 4 mm rostral to the obex, spinal transection at C2-3 or both transections together did not abolish the ION-induced bradycardia. Bradycardia induced by stimulating one ION was slightly reduced and completely abolished by unilateral and bilateral vagotomies, respectively. The ION-evoked bradycardia was also slightly reduced by a raphe lesion. This lesion together with unilateral vagotomy abolished only the bradycardia induced from the ION on the vagotomized side. In 28 left vagotomized cats, the left ION-induced bradycardia was subjected to the effects of destroying the right ION, dorsal motor/solitary nucleus (DM/SN) and ambiguous nucleus (AN). The bradycardia was completely abolished by ION lesion (7/7), greatly reduced (7/13) or completely abolished (6/13) by DM/SN lesion, and slightly increased (5/8) or decreased (3/8) by AN lesion. We concluded that cells and/or fibers in and around the ION may project fibers to the ipsilateral DM/SN and through the raphe nucleus to the contralateral ION which may send fibers to the other DM/SN.
J S
JS
Kuo
C C
CC
Wang
R H
RH
Liu
C Y
CY
Wu
C Y
CY
Chai
D000818:Animals; D001931:Brain Mapping; D002415:Cats; D004558:Electric Stimulation; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D009433:Neural Inhibition; D009847:Olivary Nucleus / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology; D011903:Raphe Nuclei / Q000502:physiology; D014630:Vagus Nerve / Q000502:physiology*