Reflex activation of postganglionic vasoconstrictor neurones supplying skeletal muscle by stimulation of arterial chemoreceptors via non-nicotinic synaptic mechanisms in sympathetic ganglia

1983 ◽  
Vol 396 (2) ◽  
pp. 95-100 ◽  
Author(s):  
W. J�nig ◽  
R. Krauspe ◽  
G. Wiedersatz
1989 ◽  
Vol 67 (10) ◽  
pp. 1199-1204 ◽  
Author(s):  
J. A. Armour

The augmentation of ventricular inotropism induced by electrical stimulation of acutely decentralized efferent sympathetic preganglionic axons was reduced, but still present, following administraiton of hexamethonium (10 mg/kg i.v.). While hexamethonium continued to be administered, the cardiac augmentations so induced were enhanced significantly following administration of the α-adrenergic receptor blocking agent, phentolamine myselate (1 mg/kg i.v.). Stimulation of the sympathetic efferent postganglionic axons in cardiopulmonary nerves induced cardiac augmentations that were unchanged following administration of these agents singly or together. The cardiac augmentations induced by stimulation of efferent preganglionic sympathetic axons were unchanged when phentolamine was administered alone. The augmentations of cardiac inotropism induced by efferent postganglionic sympathetic axonal stimulation were decreased following local administration of the β-adrenergic antagonist timolol into the ipsilateral stellate and middle cervical ganglia. Thereafter, these augmentations were unchanged following the subsequent intravenous administration of phentolamine. It is concluded that the activation of cardiac neurons in the stellate and middle cervical ganglia by stimulation of efferent preganglionic sympathetic axons can be modified by α-adrenergic receptors and that these effects are dependent upon β-adrenergic receptors, not nicotinic ones, in intrathoracic ganglia.Key words: α-adrenergic inotropism, sympathetic ganglia, hexamethonium, phentolamine.


FEBS Letters ◽  
1990 ◽  
Vol 259 (2) ◽  
pp. 269-272 ◽  
Author(s):  
F.Norman Briggs ◽  
K.Francis Lee ◽  
Joseph J. Feher ◽  
Andrew S. Wechsler ◽  
Kay Ohiendieck ◽  
...  

2008 ◽  
Vol 100 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Sarah Dutton ◽  
Paul Trayhurn

Angiopoietin-like protein 4 (Angptl4)/FIAF (fasting-induced adipose factor) was first identified as a target for PPAR and to be strongly induced in white adipose tissue (WAT) by fasting. Here we have examined the regulation of the expression and release of this adipokine in mouse WAT and in 3T3-L1 adipocytes. Angptl4/FIAF expression was measured by RT-PCR and real-time PCR; plasma Angptl4/FIAF and release of the protein in cell culture was determined by western blotting. The Angptl4/FIAF gene was expressed in each of the major WAT depots of mice, the mRNA level in WAT being similar to the liver and much higher (>50-fold) than skeletal muscle. Fasting mice (18 h) resulted in a substantial increase in Angptl4/FIAF mRNA in liver and muscle (9·5- and 21-fold, respectively); however, there was no effect of fasting on Angptl4/FIAF mRNA in WAT and the plasma level of Angptl4/FIAF was unchanged. The Angptl4/FIAF gene was expressed in 3T3-L1 adipocytes before and after differentiation, the level increasing post-differentiation; Angptl4/FIAF was released into the culture medium. Insulin, leptin, dexamethasone, noradrenaline, TNFα and several IL (IL-1β, IL-6, IL-10, IL-18) had little effect on Angptl4/FIAF mRNA levels in 3T3-L1 adipocytes. However, a major stimulation of Angptl4/FIAF expression was observed with rosiglitazone and the inflammatory prostaglandins PGD2 and PGJ2. Angptl4/FIAF does not act as an adipose tissue signal of nutritional status, but is markedly induced by fasting in liver and skeletal muscle.


2003 ◽  
Vol 95 (2) ◽  
pp. 577-583 ◽  
Author(s):  
Jianhua Li ◽  
Nicholas C. King ◽  
Lawrence I. Sinoway

Previous studies have suggested that activation of ATP-sensitive P2X receptors in skeletal muscle play a role in mediating the exercise pressor reflex (Li J and Sinoway LI. Am J Physiol Heart Circ Physiol 283: H2636–H2643, 2002). To determine the role ATP plays in this reflex, it is necessary to examine whether muscle interstitial ATP (ATPi) concentrations rise with muscle contraction. Accordingly, in this study, muscle contraction was evoked by electrical stimulation of the L7 and S1 ventral roots of the spinal cord in 12 decerebrate cats. Muscle ATPi was collected from microdialysis probes inserted in the muscle. ATP concentrations were determined by the HPLC method. Electrical stimulation of the ventral roots at 3 and 5 Hz increased mean arterial pressure by 13 ± 2 and 16 ± 3 mmHg ( P < 0.05), respectively, and it increased ATP concentration in contracting muscle by 150% ( P < 0.05) and 200% ( P < 0.05), respectively. ATP measured in the opposite control limb did not rise with ventral root stimulation. Section of the L7 and S1 dorsal roots did not affect the ATPi seen with 5-Hz ventral root stimulation. Finally, ventral roots stimulation sufficient to drive motor nerve fibers did not increase ATP in previously paralyzed cats. Thus ATPi is not largely released from sympathetic or motor nerves and does not require an intact afferent reflex pathway. We conclude that ATPi is due to the release of ATP from contracting skeletal muscle cells.


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