Electrocardiographic changes during postnatal development in conscious swine with cardiac autonomic imbalance.

Using a conscious swine model, we studied the effects of different patterns of cardiac autonomic denervation on alterations of R-R and Q T intervals for 8 postnatal weeks. Newborn pigs were assigned randomly to four different groups: sham-operated controls (C), stellate ganglion ablation (SGX), either left (LSGX) or right (RSGX), and the right cardiac vagus nerve (RCVX) transection. The ECGs were recorded by telemetry while animals rested quietly or were judged behaviorally to be asleep.

Changes in R-R and Q-T intervals following cardiac vagotomy in neonatal swine.

Asymmetric innervation of the myocardium, especially a predominance of sympathetic innervation, may establish conditions whereby electrical instability could result. Using a swine animal model, we studied the effect of right cardiac vagal denervation on the variability of R-R and Q-T intervals. Newborn pigs were assigned randomly to two groups: sham-operated controls (C), or denervation of the right cardiac vagus nerve (RCVX).

The area postrema of newborn swine is activated by hypercapnia: relevance to sudden infant death syndrome?

This study was performed to investigate a role of the neonatal area postrema (AP) in the chemoreceptor response to hypercapnia which is defective in sudden infant death syndrome (SIDS). AP responses to CO2 inhalation were monitored in 1 to 5 week old piglets by mapping neurons that were induced to express the c-fos gene product, Fos--a marker of functional activation. Interpretive confounds were minimized by controlling for hypoxia, the effects of surgical procedures and ambient environmental stressors on neuronal activity (c-fos expression).

Induction of c-fos gene expression by spinal cord transection in the rat.

Sympathetic nerve activity is maintained after high spinal injury through circuits that remain in question. We evaluated patterns of c-fos gene induction as a monitor of spinal neurons responding to high spinal cord transection in the rat. Rats were anesthetized with isofluorane.