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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using a sensory stimulation (startle) paradigm in normotensive and hypertensive rats, we evaluated the contribution of central cholinergic mechanisms to the pathology of hypertension. In normotensive Wistar-Kyoto (WKY) rats, transient airpuff stimuli elicit a complex startle reaction consisting of several behavioral and autonomic components. These include jumping (motor response), an increase in blood pressure (pressor response), an early-trial decrease in heart rate (bradycardia) and a later-trial increase in heart rate (tachycardia). Intracerebroventricular (i.c.v.) administration of cholinergic compounds to WKY rats primarily altered the bradycardia component. Thus, depletion of brain acetylcholine with hemicholinium-3 (5 micrograms/kg i.c.v.) abolished bradycardia responses without significantly affecting the motor response, tachycardia or pretest cardiovascular base-line parameters. Furthermore, enhancement of brain acetylcholine with acetylcholinesterase inhibition (physostigmine, 50 micrograms/kg i.c.v.) enhanced bradycardia in WKY rats. The nonspecific muscarinic antagonist scopolamine and the M1 muscarinic receptor antagonist pirenzepine, but neither the M2 muscarinic antagonist methoctramine nor the nicotinic antagonist hexamethonium, attenuated bradycardia. We conclude that a central M1 muscarinic receptor participates in the control of startle-associated bradycardia in the WKY rat. The spontaneously hypertensive rat does not normally exhibit startle-associated bradycardia. Because i.c.v. physostigmine revealed early-trial bradycardia in this strain, we conclude that a selective central cholinergic deficit contributes to a suppression of startle-associated bradycardia in the spontaneously hypertensive rats.
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PMID:A unique central cholinergic deficit in the spontaneously hypertensive rat: physostigmine reveals a bradycardia associated with sensory stimulation. 813 21

The airpuff startle reaction is a probe of sensori-autonomic processing and is useful for studies of genetic control of stress-induced cardiovascular activity. Using a Wistar-Kyoto-Spontaneously Hypertensive Rat F2 cross, we reported an airpuff-elicited strain-dependent and trial-dependent bradycardia, the absence of which cosegregated with hypertension. Here, we use the mapping power of the HXB-BXH recombinant inbred rat strains (n=23) to locate quantitative trait loci (QTL) for this and associated cardiovascular phenotypes. Rats (12 weeks old), with indwelling femoral arterial catheters, were subjected to repeated airpuff startle stimuli (100 ms, 12.5 psi, 28 trials). Basal mean arterial pressure (MAP), delta MAP, and delta heart rate response to airpuff stimuli were analyzed as the average over 28 trials. There was a significant strain effect on the cardiovascular phenotypes measured. One QTL for the bradycardia elicited by the first airpuff stimulus was identified on chromosome 2 (D2rat 62/63; logarithm of odds [LOD] 2.9) mapping near a reported blood pressure locus. Further QTL were identified for basal MAP (RN08), stimulus-elicited tachycardia on trials 2 to 5 (RNO1 and RNO10), and delta MAP (RNO6). Our results indicate that chromosomes 1, 2, and 10 are involved in heart rate responses to airpuff startle stimulus, and chromosomes 6 and 8 are involved in pressor responses. This study is the first to identify stress-related heart rate loci and provides additional support for our prior cosegregation results. Furthermore, we have established the utility of this experimental paradigm to identify loci responsible for cardiovascular regulation during stress in genetic hypertensive models.
Hypertension 2002 Feb
PMID:Heart rate and blood pressure quantitative trait loci for the airpuff startle reaction. 1188 71