Daily spontaneous running did not alter vagal afferent reactivity.
*Blood Pressure/drug effects; *Heart Rate/drug effects; *Physical Conditioning; Afferent Pathways/drug effects/*physiology; Analysis of Variance; Animal; Animals; Biguanides/pharmacology; Body Weight; Female; Heart/anatomy & histology/drug effects/*physiology; Hypoglycemic Agents/pharmacology; Organ Size; Rats; Sprague-Dawley; Time Factors; Vagus Nerve/drug effects/*physiology
Exercise training alters the cardiopulmonary baroreflex regulation of the circulation; however, the mechanisms responsible are unknown. One possibility is an enhanced afferent response to cardiopulmonary stimulation. We therefore tested the hypothesis that daily spontaneous running (DSR) would enhance cardiopulmonary vagal afferent responses to mechanical (increase in left atrial pressure, LAP) and chemical (phenyl biguanide, PBG) stimulation. Reactivity of single-fiber cardiopulmonary vagal afferents was evaluated in 16 control and 12 DSR anesthetized Sprague-Dawley rats. Rats were weaned at 3 wk of age and randomly assigned to a control or DSR group. Eight to twelve weeks of DSR was associated with a 27% increase in heart weight-to-body weight ratio (3.27 +/- 0.08 vs. 2.56 +/- 0.05 g/kg, P \textless 0.001) and resting bradycardia (394 +/- 10 vs. 421 +/- 8 beats/min, P = 0.036). However, DSR did not alter the stimulus-response curves to increases in LAP (frequency of discharge vs. LAP) for either the high-frequency (maximum response, sedentary 59.6 +/- 3.2, DSR 60.1 +/- 5.0 spikes/s) or low-frequency (maximum response, sedentary 20.0 +/- 2.9 DSR 20.6 +/- 3.9 spikes/s) receptors. Dose-response curves to chemical stimulation (spikes/s vs. PBG dose) were also not altered by DSR. Thus DSR did not change vagal afferent reactivity to mechanical or chemical stimulation.
Scislo T J; DiCarlo S E; Collins H L
The American journal of physiology
1993
1993-11
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.1993.265.5.H1564" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.1993.265.5.H1564</a>
Endothelin-mediated in vivo pressor responses following TRPV1 activation.
*Blood Pressure/drug effects; *Vasoconstriction/drug effects; Adrenergic alpha-Agonists/administration & dosage; Analysis of Variance; Animal; Animals; Azepines/administration & dosage; Biphenyl Compounds/administration & dosage; Capsaicin/administration & dosage; Cells; Cultured; Diabetes Mellitus; Diabetic Angiopathies/genetics/*metabolism/physiopathology; Dipeptides/administration & dosage; Disease Models; Dose-Response Relationship; Drug; Endothelial Cells/metabolism; Endothelin A Receptor Antagonists; Endothelin A/metabolism; Endothelin B Receptor Antagonists; Endothelin B/metabolism; Endothelin-1/*metabolism; Enzyme-Linked Immunosorbent Assay; Femoral Artery/drug effects/*metabolism/physiopathology; Inbred C57BL; Indoles/administration & dosage; Infusions; Intravenous; Knockout; Male; Mice; Phenylephrine/administration & dosage; Receptor; TRPV Cation Channels/agonists/deficiency/genetics/*metabolism; Type 2/genetics/*metabolism/physiopathology; Vasoconstrictor Agents/administration & dosage
Transient receptor potential vanilliod 1 (TRPV1) channels have recently been postulated to play a role in the vascular complications/consequences associated with diabetes despite the fact that the mechanisms through which TRPV1 regulates vascular function are not fully known. Accordingly, our goal was to define the mechanisms by which TRPV1 channels modulate vascular function and contribute to vascular dysfunction in diabetes. We subjected mice lacking TRPV1 [TRPV1((-/-))], db/db, and control C57BLKS/J mice to in vivo infusion of the TRPV1 agonist capsaicin or the alpha-adrenergic agonist phenylephrine (PE) to examine the integrated circulatory actions of TRPV1. Capsaicin (1, 10, 20, and 100 mug/kg) dose dependently increased MAP in control mice (5.7 +/- 1.6, 11.7 +/- 2.1, 25.4 +/- 3.4, and 51.6 +/- 3.9%), which was attenuated in db/db mice (3.4 +/- 2.1, 3.9 +/- 2.1, 7.0 +/- 3.3, and 17.9 +/- 6.2%). TRPV1((-/-)) mice exhibited no changes in MAP in response to capsaicin, suggesting the actions of this agonist are specific to TRPV1 activation. Immunoblot analysis revealed decreased aortic TRPV1 protein expression in db/db compared with control mice. Capsaicin-induced responses were recorded following inhibition of endothelin A and B receptors (ET(A) /ET(B)). Inhibition of ET(A) receptors abolished the capsaicin-mediated increases in MAP. Combined antagonism of ET(A) and ET(B) receptors did not further inhibit the capsaicin response. Cultured endothelial cell exposure to capsaicin increased endothelin production as shown by an endothelin ELISA assay, which was attenuated by inhibition of TRPV1 or endothelin-converting enzyme. TRPV1 channels contribute to the regulation of vascular reactivity and MAP via production of endothelin and subsequent activation of vascular ET(A) receptors. Impairment of TRPV1 channel function may contribute to vascular dysfunction in diabetes.
Ohanyan Vahagn A; Guarini Giacinta; Thodeti Charles K; Talasila Phani K; Raman Priya; Haney Rebecca M; Meszaros J Gary; Damron Derek S; Bratz Ian N
American journal of physiology. Heart and circulatory physiology
2011
2011-09
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.00082.2011" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.00082.2011</a>
Gender difference in cardiopulmonary reflex inhibition of sympathetic nerve activity.
*Blood Pressure/drug effects; *Heart Rate/drug effects; *Reflex/drug effects; Analysis of Variance; Animals; Biguanides/pharmacology; Denervation; Female; Laryngeal Nerves/physiology; Male; Phenylephrine/pharmacology; Pulmonary Circulation/drug effects/physiology; Rats; Sex Characteristics; Sinoatrial Node/*physiology; Sympathetic Nervous System/drug effects/*physiology
We tested the hypothesis that reflex responses to mechanical [increase in left atrial pressure (LAP) 0-25 mmHg] and chemical stimulation [left atrial injection of phenylbiguanide (PBG), 0.5-10 mg/kg] of cardiopulmonary receptors are greater in female (n = 9; 335 +/- 9 g) than in male (n = 10; 558 +/- 23 g) age-matched rats. Anesthetized (500 mg/kg urethan and 80 mg/kg alpha-chloralose), tracheotomized, and artificially ventilated (100% oxygen), sinoaortic-denervated animals were instrumented with left atrial, femoral venous, and arterial catheters and a Tygon occluder around the ascending aorta. Reflex inhibition of lumbar sympathetic nerve activity (LSNA) vs. LAP and dose PBG was higher in female rats. A two-way analysis of variance revealed a significant gender effect, males vs. females (P = 0.023), and a significant gender x dose interaction (P \textless 0.001) for LSNA vs. LAP. There was also a significant gender x dose interaction (P \textless 0.001) for LSNA vs. PBG. However, there was no influence of gender on the reflex inhibition of mean arterial pressure (P = 0.751) or heart rate (P = 0.561). These responses were associated with a higher left ventricular weight-to-body weight ratio in females (2.14 +/- 0.06 vs. 1.95 +/- 0.07 g/kg, P = 0.039).
Scislo T J; DiCarlo S E
The American journal of physiology
1994
1994-10
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.1994.267.4.H1537" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.1994.267.4.H1537</a>