Issue Archive

Effects of soman and morphine on the phrenic and external intercostal nerve discharges of the cat

Huang Wuxin, Liu Churngui

Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences. Beijing, China

Abstract

Discharges of the phrenic and external intercostal nerve fibers were recorded simultaneously on the cats anesthetized with urethane and chloralose. During quiet respiration, the phrenic and external intercostal nerve single fibers had no statistically significant differences in duration of bursts, number of impulses, impulse frequency and duration of silent period. After bilateral vagotomy, both phrenic and external intercostal nerve fibers had longer duration of bursts and higher frequency of impulses. During asphyxia, both phrenic and external intercostal nerves increased activityat first, then ceased firing at the same moment. After the administration of 0.2-3 #mu#g soman into vertebral artery or 10-20 #mu#g/kg into femoral vein, the phrenic firing was inhibited and at that moment the external intercostal nerve did not stop firing (type I reaction) in 40 of 47 (85 %) and 13 of 15 (87%) cats respectively. In all of these cats, we never saw type III reaction (external intercostal firing stopped while phrenic nerve was still firing). On the contrary, administration of 0.5-5 mg morphine into vertebral artery resulted in type III reaction in 7 of 12 cats (58%) but no type I reaction was observed. After cotton paper soaking up 2 #mmu#g soman was placed on the ventral surface of cervical spinal cord in which phrenic motoneurons are located, the rhythmic phrenic nerve activity did not stop. The results suggest that dorsal respiratory group which innervates phrenic nerve mainly and ventral respiratory group which innervates external intercostal nerve mainly have similar activity during quiet respiration, vagotomy and asphyxia; while these two groups changed their activity in different ways after, soman and morphine were administered into vertebral artery.

Key words: Phrenfic nerve;Intercostal nerve;Nerve fiber potential;Soman;Morphine

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Huang Wuxin, Liu Churngui. Effects of soman and morphine on the phrenic and external intercostal nerve discharges of the cat. Acta Physiol Sin 1985; 37 (2): (in Chinese with English abstract).