application) The activation of cardiac sympathetic afferents during ischemia is responsible for conveying cardiac nociception and initiating neural reflexes which lead to hemodynamic alterations and arrhythmias. """"""""Silent"""""""" afferents (afferents exhibiting no spontaneous activity and unresponsive to physiological stimuli) are known to play a critical role in nociception, however it remains uncertain whether the heart is innervated by silent cardiac sympathetic afferents. Furthermore, the role of many ischemic metabolites in activation of ischemia-sensitive cardiac sympathetic afferents remains to be established. The following hypotheses will be tested: 1. the heart is innervated by a population of silent sympathetic afferents which function primarily as nociceptors; and 2. myocardial ischemia increases protons and amphipathic lipid metabolites (palmitylcarnitine and lysophosphatidylcholine) concentrations in the myocardial interstitial fluid which contribute to the activation of cardiac sympathetic afferents. The investigator proposes to initially demonstrate the presence of silent cardiac afferents utilizing a stimulating electrode as a search stimulus. The investigator will then determine the responses of silent cardiac sympathetic afferents to cardiac distension, myocardial ischemia, and algesic chemicals. In addition, the investigator plans to use cardiac microdialysis to document the production of protons/lactic acid and amphipathic lipid metabolites in the myocardial interstitial fluid during ischemia. Finally, the investigator will record single-unit activity of afferents to evaluate the role of protons and amphipathic lipid metabolites in the activation of ischemia-sensitive cardiac afferents by buffering the pH of the afferent's receptive field and inhibiting the activity of carnitine acyltransferase-I, respectively. The proposed research will provide insights into the neural encoding mechanism of cardiac nociception and mechanisms of activation of cardiac nociceptors during ischemia. Such information may also suggest alternate interventions designed to treat intractable angina pectoris and to limit potentially dangerous cardiac reflexes.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
7R01HL060026-04
Application #
6346986
Study Section
Experimental Cardiovascular Sciences Study Section (ECS)
Project Start
1998-04-01
Project End
2002-03-31
Budget Start
2000-07-01
Budget End
2002-03-31
Support Year
4
Fiscal Year
2000
Total Cost
$168,906
Indirect Cost
Name
Pennsylvania State University
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
129348186
City
Hershey
State
PA
Country
United States
Zip Code
17033
Li, De-Pei; Chen, Shao-Rui; Pan, Hui-Lin (2010) Adenosine inhibits paraventricular pre-sympathetic neurons through ATP-dependent potassium channels. J Neurochem 113:530-42
Li, De-Pei; Yang, Qing; Pan, Hao-Min et al. (2008) Plasticity of pre- and postsynaptic GABAB receptor function in the paraventricular nucleus in spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 295:H807-15
Li, De-Pei; Yang, Qing; Pan, Hao-Min et al. (2008) Pre- and postsynaptic plasticity underlying augmented glutamatergic inputs to hypothalamic presympathetic neurons in spontaneously hypertensive rats. J Physiol 586:1637-47
Yang, Q; Chen, S-R; Li, D-P et al. (2007) Kv1.1/1.2 channels are downstream effectors of nitric oxide on synaptic GABA release to preautonomic neurons in the paraventricular nucleus. Neuroscience 149:315-27
Li, De-Pei; Pan, Hui-Lin (2007) Role of gamma-aminobutyric acid (GABA)A and GABAB receptors in paraventricular nucleus in control of sympathetic vasomotor tone in hypertension. J Pharmacol Exp Ther 320:615-26
Wu, Zi-Zhen; Pan, Hui-Lin (2007) Role of TRPV1 and intracellular Ca2+ in excitation of cardiac sensory neurons by bradykinin. Am J Physiol Regul Integr Comp Physiol 293:R276-83
Chen, Qian; Pan, Hui-Lin (2007) Signaling mechanisms of angiotensin II-induced attenuation of GABAergic input to hypothalamic presympathetic neurons. J Neurophysiol 97:3279-87
Zahner, Matthew R; Li, De-Pei; Pan, Hui-Lin (2007) Benzodiazepine inhibits hypothalamic presympathetic neurons by potentiation of GABAergic synaptic input. Neuropharmacology 52:467-75
Li, De-Pei; Pan, Hui-Lin (2007) Glutamatergic inputs in the hypothalamic paraventricular nucleus maintain sympathetic vasomotor tone in hypertension. Hypertension 49:916-25
Chen, Q; Pan, H-L (2006) Regulation of synaptic input to hypothalamic presympathetic neurons by GABA(B) receptors. Neuroscience 142:595-606

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