Influence of cardiac neural inputs on rhythmic variations of heart period in the cat

Abstract

Spectral analysis was used to investigate variations of heart period in 13 decerebrate cats under different conditions of neural input to the heart. Spectral density plots in intact animals showed three well-defined peaks: P1 (1.5-2.5 cycles/min), P2 (6-10 cycles/min), and P2 (respiratory frequency). In the presence of sympathetic input only the amplitudes of all peaks were decreased; when only vagal input was present the amplitudes of P1 and P2 were increased and there was no change in P3; when neither sympathetic nor vagal input was present the amplitudes of all peaks were decreased. In addition, the amplitudes of P1 and P2 were increased and there was no change in P3; when neither sympathetic nor vagal input was present the amplitudes of all peaks were decreased. In addition, the amplitudes of P1 and P2 were found to be significantly correlated with the mean heart period under the condition of vagal control only. It is concluded that P3 is related to sinus arrhythmia and that P1 and P2 may be related to spontaneous rhythms that are an intrinsic feature of the dynamic regulation of heart period by the vagus system. Sympathetic activity plays no role in the genesis of these rhythms.

Regulation of Heart Rate Variation by the Autonomic Nervous System in Neonatal Lambs

“…baroreflex is weaker than in adults (16). There has been controIn both age groups, the percentage of low frequencies (less than versial information about whether HRV is, as with the sino-atrial six oscillations per m i d , measured as relative Power density, node, under dual autonomic control (17)(18)(19)(20)(21)(22)(23)(24). Our results indicate increased.…”

Disfunção parassimpática, variabilidade da freqüência cardíaca e estimulação colinérgica após infarto agudo do miocárdico

“…Em outras palavras, a análise espectral decompõe a variabilidade total da FC em seus componentes causadores, apresentando-os segundo a freqüência com que alteram a FC. Independente do método utilizado para cálculo da densidade espectral (transformação rápida de Fourrier ou modelo auto-regressivo), delimitam-se normalmente quatro faixas de freqüências distintas, ilustradas na figura 1: 1) alta freqüência (AF: 0,15 a 0,40 Hz), modulada pelo sistema nervoso parassimpático e gerado pela respiração 40 ; 2) baixa freqüência (BF: 0,04 a 0,15 Hz), modulada tanto pelo simpático quanto pelo parassimpático 37,41 . Tem sido correlacionada ao sistema barorreceptor e termorregulador 42 , à atividade periférica vasomotora e ao sistema reninaangiotensina 30,33 ; 3) muita baixa freqüência (MBF; 0,01 à 0,04 Hz) tem sido proposta como um marcador da atividade simpática 33 , porém isto ainda não está bem definido; 4) ultra baixa freqüência (UBF: 10 -5 à 10 -2 Hz sua correspondência fisiológica ainda permanece obscura 33 .…”

Synaptic delay in the heart: an ionophoretic study.

“…But they were often seen 36 at 37 0C when the resting rate was 1-2 Hz. Spontaneous oscillations of similar period are known to occur in intact hearts, whether isolated or in 8itu (Lovatt Evans, 1933;Chess, Tam & Calaresu, 1975).…”