The purpose of this study was to identify changes in venomotor tone in the chronic low-dose angiotensin II (Ang II) model of hypertension and to establish the contribution of sympathetic nerve activation to these venomotor tone changes. Male Sprague-Dawley rats were acclimatized to a 0.4% or 2.0% NaCl diet for 7 days and then catheterized to allow chronic and repeated measures of arterial press...

Administration of abdominal radiotherapy results in small intestinal motor dysfunction. We have developed a rat radiation enteritis model that, after exposure in vivo, shows high-amplitude, long-duration (HALD) pressure waves in ex vivo ileal segments. These resemble in vivo dysmotility where giant contractions migrate both antegradely and retrogradely. Mediation of these motor patterns is uncl...

Chen X, Patel K, Connors SG, Mendonca M, Welch WJ, Wilcox CS. Acute antihypertensive action of Tempol in the spontaneously hypertensive rat. Am J Physiol Heart Circ Physiol 293: H3246–H3253, 2007. First published October 12, 2007; doi:10.1152/ajpheart.00957.2007.—Acute intravenous Tempol reduces mean arterial pressure (MAP) and heart rate (HR) in spontaneously hypertensive rats. We investigated...

The renal circulation of the dog was studied by a rheoplethysmographic method capuble of simultaneously recording the time courses of volume, rate, and acceleration of inflow, outflow and difference between inflow and outflow of blood. The studies were done first under control conditions and then under conditions of relatively acute circulatory change induced by intravenous injection of norepin...

The actions of ACh antagonists were studied on synaptic currents of autonomic ganglia of the frog. Fast excitatory synaptic currents (ESCs) were recorded from cardiac and paravertebral neurons with the use of the 2-microelectrode voltage-clamp method. The actions of 4 ACh antagonists, tubocurarine, hexamethonium, trimetaphan, and decamethonium were studied. Tubocurarine was effective at reducin...

AIMS The role of the vagus in the ventricle is controversial, although the vagus can protect against ventricular fibrillation (VF) via nitric oxide (NO). This study aims to determine whether the mechanisms involved are dependent on post-ganglionic release and muscarinic receptor activation. For this purpose, NO release and electrophysiological effects of vagus nerve stimulation (VNS) were evalu...

OBJECTIVE In the present study, the peripheral mechanism that mediates the pressor effect of angiotensin-(1-7) in the rostral ventrolateral medulla was investigated. METHOD Angiotensin-(1-7) (25 pmol) was bilaterally microinjected in the rostral ventrolateral medulla near the ventral surface in urethane-anesthetized male Wistar rats that were untreated or treated (intravenously) with effectiv...

Cholera toxin (CT) may induce uncontrolled firing in recurrent networks of secretomotor neurons in the submucous plexus. This hypothesis was tested in chloralose-anesthetized rats in vivo. The secretory reflex response to graded intestinal distension was measured with or without prior exposure to luminal CT. The transmural potential difference (PD) was used as a marker for electrogenic chloride...

Spectral analysis of cardiovascular signals has been extensively used to investigate circulatory homeostatic mechanisms. However, the nature of very low-frequency (VLF) fluctuations remains unclear. Because we previously observed enhanced VLF fluctuations in blood pressure (BP) in the sympathectomized rat (a model characterized by markedly increased plasma epinephrine levels), the aims of our s...

The activation of autoreceptors is known to be important in the modulation of presynaptic transmitter secretion in peripheral and central neurons. Using whole-cell recordings made from the free growth cone of myocyte-contact motoneurons of Xenopus cell cultures, we have observed spontaneous nerve terminal currents (NTCs). These spontaneous NTCs are blocked by d-tubocurarine (d-TC) and alpha-bun...