Cardiovascular Reflex Control by Afferent Fibers from Skeletal Muscle Receptors

Mitchell, Jere H.; Schmidt, Robert F.

doi:10.1002/cphy.cp020317

Cited by 131 publications

(103 citation statements)

References 187 publications

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“…The opposite regulation of CGRP and amylin after glucose ingestion stresses the importance of separate specific assays for measurement of circulating concentrations of these peptides. Because CGRP is present in class 4 sensory afferent nerve fibers (16), which are abundant in skeletal muscle (17), the local concentration of CGRP in skeletal muscle may be considerably higher than the simultaneous plasma concentration. It is therefore possible that, although CGRP is only present in picomolar concentrations in plasma, it reaches local concentrations in excess of the 10~9 M reported to be required to alter skeletal muscle carbohydrate metabolism (5,12).…”

Section: Resultsmentioning

confidence: 99%

Effects of Meal Ingestion on Plasma Amylin Concentration in NIDDM and Nondiabetic Humans

Butler¹,

Chou²,

Carter³

et al. 1990

Diabetes

259

136

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Recent interest has focused on the potential role of amylin in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). This 37-amino acid peptide is found in extracellular amyloid deposits in -5 0 % of pancreatic islets of patients with NIDDM and has been shown to inhibit skeletal muscle glycogen synthesis in vitro. Immunocytochemical studies have colocalized amylin and insulin within p-cell secretory granules in nondiabetic humans, provoking the following questions. Is amylin cosecreted with insulin? Are circulating amylin concentrations higher in patients with NIDDM either before or after food ingestion? To answer these questions, we developed a sensitive and specific immunoassay to measure plasma concentrations of amylin in humans. Use of this assay indicated that, in lean nondiabetic subjects, glucose ingestion resulted in an increase (P < 0.001) in the plasma concentration of amylin (from 2.03 ± 0.22 to 3.78 ± 0.39 pM) and insulin (from 48.3 ± 3.1 to 265 ± 44 pM). There was a significant correlation between the concentrations of insulin and amylin (r = 0.74, P < 0.001) and the increase in insulin and amylin concentration (r = 0.65, P < 0.005). Fasting concentrations of amylin did not differ in diabetic and weight-matched nondiabetic subjects and showed a similar pattern of change after ingestion of a mixed meal. We conclude that amylin is secreted in response to ingestion of either glucose or a mixed meal and circulates at concentrations that do not differ in patients with NIDDM and nondiabetic subjects. It remains to be determined whether amylin at physiological concentrations influences carbohydrate metabolism and if so whether its effects differ in diabetic and nondiabetic humans.

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Section: Resultsmentioning

confidence: 99%

Effects of Meal Ingestion on Plasma Amylin Concentration in NIDDM and Nondiabetic Humans

Butler¹,

Chou²,

Carter³

et al. 1990

Diabetes

259

136

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“…After measuring these control cardiovascular responses, the dose-response effect of microdialyzing clonidine was determined. This was done by perfusing clonidine at doses of 3.8 .Lmol/L, 38 ,mol/L, 380 lrmolIL, and 30 Hz, 0.1 millisecond duration) during a 10-minute collection period ( Table 1). The alternate stimulation-evoked contraction was performed so that the muscle did not fatigue rapidly.…”

Section: Experiments 1 (Protocol)mentioning

confidence: 99%

Effects of clonidine on the reflex cardiovascular responses and release of substance P during muscle contraction.

Ally

Meintjes

Mitchell

et al. 1994

Circulation Research

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The effects of microdialyzing clonidine into the L-7 dorsal horn on the cardiovascular responses, renal sympathetic nerve activity (RSNA), and release of substance P (SP) evoked by static contraction of the triceps surae muscle were studied using anesthetized cats. A microdialysis probe was inserted into the spinal cord ipsilateral to the muscle being contracted or stretched. Contraction, evoked by stimulation of the distal ends of the cut L-7 and S-1 ventral roots for 1 minute, increased mean arterial pressure (MAP), heart rate (HR), and RSNA by 48+6 mm Hg, 18+2 beats per minute, and 66±5%, respectively. Passive stretch of the same muscle for 1 minute also increased MAP, HR, and RSNA by 51±6 mm Hg, 17+2 beats per minute, and 50+3%, respectively. . These results demonstrate that stimulation of a2-adrenergic receptors in the L-7 dorsal horn attenuates the cardiovascular responses and RSNA changes to static contraction and passive stretch. This attenuation by clonidine appears not to be mediated through presynaptic inhibition of SP release. (Circ Res. 1994;75:567-575.) Key Words * exercise pressor reflex * passive stretchsympathetic nerve activity * a2-adrenergic receptor .yohimbine Static muscle contraction evokes increases in arterial pressure (AP), heart rate (HR), cardiac contractility, and renal sympathetic nerve activity (RSNA) in anesthetized cats.1-6 These changes are a reflex arising from the contracting muscle, which is commonly known as the "exercise pressor reflex."4 The reflex cardiovascular and sympathetic nerve activity responses are initiated by a contraction-induced activation of thinly myelinated (group III) and unmyelinated (group IV) muscle afferents. The majority of the group III afferents display mechanosensitivity; ie, their endings respond to mechanical stimuli, whereas the majority of the group IV afferents respond to metabolic changes.7,8 The dorsal horn of the spinal cord is the site of the first synapse of the majority of group III and group IV muscle afferents.9'10 Thus, this region may play an important role in the reflex cardiovascular changes observed during muscle contraction. A variety of neurotransmitters and/or neuromodulators of group III and group IV afferents have been identified in the dorsal

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“…It was also confirmed that these responses were reflexly induced by the stimulation, since they were abolished by a local administration of lidocaine into the subcutaneous area where the electrodes were attached. Following the earlier report of Hunt [13] suggesting that the peripheral nerves contained two types of afferents, i.e., "pressor and depressor fibers," many investigators have reported regarding the mechanism of blood pressure responses to somatic afferent stimulation [14]. The previous studies have shown that these opposite responses in arterial pressure to somatic afferent stimulation seem to be produced by a different depth of anesthesia [15,16] and a different type of afferent fiber group [14].…”

Section: Discussionmentioning

confidence: 98%

Effects of Electrical Stimulation of the Dorsal Skin on Systemic and Mesenteric Microvascular Hemodynamics in Anesthetized Rats.

Yamaguchi

Ito²,

Ohshima³

2002

JJP

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Cardiovascular Reflex Control by Afferent Fibers from Skeletal Muscle Receptors

Cited by 131 publications

References 187 publications

Effects of Meal Ingestion on Plasma Amylin Concentration in NIDDM and Nondiabetic Humans

Effects of Meal Ingestion on Plasma Amylin Concentration in NIDDM and Nondiabetic Humans

Effects of clonidine on the reflex cardiovascular responses and release of substance P during muscle contraction.

Effects of Electrical Stimulation of the Dorsal Skin on Systemic and Mesenteric Microvascular Hemodynamics in Anesthetized Rats.

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