Developmental changes in heart rate variability during exposure to prolonged hypercapnia in piglets.

The hypothesis that hypercapnia-induced differences in heart rate variability (HRV) would emerge during early maturation was tested using a developing porcine model. Piglets were randomly assigned to either exposed (10% CO2 for 1 h) or control (100% O2) conditions, and then to one of three study groups: (a) 5-8 days old, (b) 13-15 days old, (c) 26-34 days old. Experiments were performed on pairs of age-and litter-matched animals that were anesthetized, paralyzed, and artificially ventilated.

Baroreceptor-related dysrhythmias in piglets with selective autonomic denervation of the heart.

This study was carried out to determine whether selective cardiac autonomic denervation performed on neonatal swine would evoke dysrhythmias later in development. Piglets (n = 27; 5-10 days old) underwent unilateral stellate ganglion ablation, or right cardiac vagotomy, or sham surgery. Fifty to sixty days after denervation, acute experiments were performed to evaluate responses to baroreceptor activation.

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.

Rhythmicities in sympathetic discharge: a signal of cardiorespiratory integration in developing animals.

We have been pursuing various avenues of investigation to elucidate the postnatal maturation of neural regulation of cardiovascular and respiratory integration. In this paper we present our results from a systematic analysis of age-related modulations of sympathetic (SYMP) activity with respect to experimental alterations in baroreceptor afferent inputs. The three age groups of piglets were chosen based on different responses to a complex stimulus, i.

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).