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1. In vagotomized, paralyzed, decerebrate cats, simultaneous recordings were taken from one or more sympathetic nerves [cervical sympathetic (CS), inferior cardiac (IC), splanchnic (SP)] and from medullary neurons in vasomotor-related regions. Coherence analyses were used to ascertain the presence of sympathetic rhythms (2-6 Hz or "3-Hz rhythm," 7-13 Hz or(More)
1. In decerebrate paralyzed cats, we observed the responses of ventral and dorsal medullary inspiratory (I) neurons to two types of vagal afferent input that shorten neural I: lung inflation and vagal electrical stimulation. 2. A study population of 15 I neurons whose firing patterns suggested involvement in the inspiratory OFF-switch (IOS) was selected on(More)
1. Inspiratory (I) activities of recurrent laryngeal (RL) motoneurons and efferent nerves were studied by autospectral, interval, and coherence analyses, with emphasis on fast rhythms of two types: medium-frequency oscillations (MFO, usual range 20-50 Hz for nerve autospectral peaks) and high-frequency oscillations (HFO, usual range 50-100 Hz). 2. In(More)
1. In midcollicular decerebrate, unanesthetized, paralyzed cats ventilated with a cycle-triggered pump system, the properties of high-frequency oscillations (HFOs, 50-100 Hz) in membrane potentials (MPs) of medullary inspiratory (I) and expiratory (E) cells were studied. Simultaneous recordings were taken from bilateral phrenic and recurrent laryngeal (RL)(More)
The hypothesis that augmentation of the carotid chemoreceptor response to hypoxia by almitrine is due in part to an increased response to CO2 was tested by using single or few fiber preparation of carotid body chemosensory fibers in 12 cats anesthetized with alpha-chloralose. To differentiate between the plausible mechanisms of effects, we also tested the(More)
To test the hypothesis that peripheral chemoreflex effect on the preganglionic cervical sympathetic nerve (PSN) activity is entirely mediated by the central respiratory drive (CRD), as expressed in the phrenic nerve (PN) activity, we studied the relationship between PN and PSN activities under controlled conditions of carotid chemosensory excitation in the(More)
1. In seven decerebrate cats, recordings were taken from the preganglionic cervical sympathetic (CSy) nerves and from 74 individual CSy fibres. Correlation and spectral analyses showed that nerve and fibre discharges had several types of rhythm that were coherent (correlated) between population and unit activity: respiratory, '3 Hz' (2-6 Hz, usually cardiac(More)
Carotid body chemosensory activities were measured before and after 0.2, 5,6 and 7 h of sustained isocapnic (PaCO(2) approximately equal to 30 Torr) hypoxia (PaO(2) approximately equal to 43 Torr) in the cats (n=7). The activity increased from 5.4 impsec(-1) at 0.2 h to about 13 impsec(-1) at 7 h. This increase in chemosensory activities were due to both an(More)
The hypothesis that the maximal response to pCO2 of carotid body chemoreceptors would be the same regardless of pO2, if the receptor molecule behaves like a hemoglobin molecule, was investigated using single or a few fiber carotid body chemoreceptors in cats in vivo which were anesthetized and artificially ventilated. In one series, graded levels of CO2(More)
It is known that atrial natriuretic peptide (ANP) is released from cardiac myocyte and other stores during hypoxia and is involved in pulmonary-cardiovascular reflexes and in natriuresis and diuresis. Since the carotid body initiates hypoxic chemoreflexes, we hypothesized that ANP could potentiate the hypoxic stimulation of the carotid body chemoreceptor in(More)