Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.11.18 (MAP)
 7,412 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The present study was designed to investigate the role of cardiopulmonary reflex, more specifically the Bezold-Jarisch reflex, in experimental hypertension induced by chronic administration of Nw-nitro-L-arginine methyl ester (L-NAME) (0.5 mg/ml) added to the drinking water for 6 days. The study was performed in male Wistar rats (200-350 g), 9 animals per group. L-NAME ingestion caused a significant increase in resting mean arterial pressure (MAP: 182 +/- 4 mmHg) and heart rate (HR: 447 +/- 20 bpm) when compared to untreated rats (MAP: 112 +/- 3 mmHg and HR: 355 +/- 10 bpm). Cardiopulmonary receptors were chemically stimulated with bolus injections of 5-hydroxytryptamine (5-HT, 4-10 micrograms/kg, iv) followed by measuring the falls in diastolic arterial pressure (DAP) and HR in conscious and freely moving animals. As expected, the responses to intravenous injections of 5-HT consisted of a dose-dependent reduction in HR (from 26 +/- 14 to 175 +/- 25 bpm) and DAP (from 7 +/- 4 to 39 +/- 3 mmHg) in the control rats. Both bradycardia and diastolic hypotension were significantly accentuated in the L-NAME animals (approximately 30%). These data suggest that, in contrast to other models of hypertension, in the present one caused by inhibition of nitric oxide synthesis, the Bezold-Jarisch reflex is exaggerated. This neural dysfunction could be related to changes in the cardiac vagal efferent or effector.
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PMID:Exaggerated Bezold-Jarisch reflex in the hypertension induced by inhibition of nitric oxide synthesis. 858 Aug 77

The Bezold-Jarisch reflex function was evaluated in rats made hypertensive by the chronic oral intake of a nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME, averaging 35 mg/kg/day), for 3, 6, and 12 days (n = 9/group) and in untreated control rats (CR, n = 9/group). L-NAME-treated rats showed a marked hypertension (MAP: 148 +/- 3, 182 +/- 4, and 179 +/- 4 mm Hg, respectively) compared with CR (110 +/- 2 mm Hg). The 6- and 12-day groups showed tachycardia (447 +/- 20 and 466 +/- 13 beats/min, respectively) when compared with CR (355 +/- 10 beats/min). When compared with CR, left ventricular hypertrophy was observed in rats treated with L-NAME for 6 and 12 days. The Bezold-Jarisch reflex, a decrease in heart rate (HR) accompanied by a decrease in diastolic arterial pressure (DAP), was evoked in a dose dependent manner by the intravenous injection of 5-hydroxytryptamine (5-HT, 5 to 10 microg/kg). Relative to responses observed in CR, 5-HT at 10 microg/kg caused a four- to fivefold greater decrease in HR and a two- to threefold greater decrease in DAP in all the L-NAME treatment groups. Using a Langendorff technique, we observed a significant increase in the responsiveness of the pacemaker to acetylcholine (1.25 to 80 microg/mL). These data suggest that the pharmacological inhibition of the nitric oxide synthase causes profound changes in the mechanisms of cardiovascular regulation as shown by a marked enhancement of the Bezold-Jarisch reflex in L-NAME-treated rats. The enhancement of this reflex seems to be in great part due to the hyperresponsiveness of the cardiac pacemaker to cholinergic stimulation.
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PMID:Inhibition of nitric oxide synthase causes profound enhancement of the Bezold-Jarisch reflex. 950 52

Propofol may cause profound bradycardia and asystole, which are mediated indirectly via cardiac innervation but could involve direct effects on the sino-atrial (SA) node and the conducting system of the heart. To test the hypothesis that propofol may also activate Bezold-Jarisch reflexes to cause bradycardia, 5-hydroxytryptamine (5-HT), veratridine and propofol were injected into the left ventricle of the heart in both intact and vagotomized rabbits. 5-HT and veratridine produced an acute, rapid, dose-dependent decrease in mean heart rate (delta HR) and a decrease in mean arterial pressure (delta MAP) together with transient but severe depression and abolition of renal sympathetic nerve activity (RSNA). Bilateral vagotomy greatly attenuated these responses; for example, at the highest dose of 5-HT (8 micrograms kg-1), delta HR, delta MAP and duration of abolition of RSNA were reduced by 57% (P < 0.001), 53% (P < 0.05) and 79% (P < 0.05), respectively. In contrast, reductions in delta HR and delta MAP produced by propofol were statistically significant only at very high doses (8 mg kg-1). Propofol depressed but did not abolish RSNA, and bilateral vagotomy had no effect on any of these responses. These results indicate that the cause of acute bradycardia after administration of propofol does not involve the Bezold-Jarisch reflex.
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PMID:Propofol, bradycardia and the Bezold-Jarisch reflex in rabbits. 1043 26

While atrial and B-type natriuretic peptides (ANP and BNP) have been shown to enhance reflex responses attributed to cardiac vagal afferents, their effects on arterial baroreceptor reflex function remain controversial. The actions of C-type natriuretic peptide (CNP) in this regard are unknown. To clarify their actions on arterial baroreflexes, we tested whether i.v. infusions of ANP, BNP or CNP at 10 pmol kg(-1) min(-1) modified the steady-state mean arterial blood pressure-heart rate (MAP-HR) relationship in conscious sheep. At this dose, all three natriuretic peptides are known to enhance the cardiac chemoreflex response to phenylbiguanide (Bezold-Jarisch reflex). Sigmoid MAP-HR relationships were constructed from the steady-state responses to alternating injections of vasopressor (phenylephrine, 1-15 microg kg(-1)) and vasodepressor agents (nitroprusside, 1-15 microg kg(-1)) in the absence and presence of infused ANP, BNP or CNP (tested in random order at least 1 week apart). No parameter of the steady-state baroreflex relationship was significantly altered by infusion of any of the three natriuretic peptides. We conclude that in conscious sheep, normal arterial baroreceptor-HR reflex function prevails in the presence of moderate doses of ANP, BNP or CNP.
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PMID:Do natriuretic peptides modify arterial baroreflexes in sheep? 1536 78