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

Cannabinoids, including the endogenous ligand anandamide (arachidonyl ethanolamide), elicit pronounced hypotension in rats via activation of peripherally located CB1 cannabinoid receptors, which have been also implicated in endotoxin (lipopolysaccharide [LPS])-induced hypotension. The present study was designed to test the role of vascular CB1 receptors in cannabinoid- and endotoxin-induced mesenteric vasodilation. In the isolated, buffer-perfused rat mesenteric arterial bed precontracted with phenylephrine, anandamide induced long-lasting (up to 60 minutes) dose-dependent vasodilation (ED50: 79+/-3 nmol; maximal relaxation: 77+/-2%), inhibited by 0.5 to 5.0 micromol/L of the selective CB1 receptor antagonist SR141716A. Low doses of the calcium ionophore ionomycin also caused mesenteric vasodilation inhibited by SR141716A. The metabolically stable analogue R-methanandamide elicited mesenteric vasodilation (ED50: 286+/-29 nmol), whereas the potent synthetic CB1 receptor agonists WIN 55212-2 and HU-210 caused no change in vascular tone or only a minor dilator effect not affected by SR141716A, respectively. The endogenous ligand 2-arachidonyl glycerol caused no change in vascular tone, whereas Delta9-tetrahydrocannabinol and arachidonic acid caused mesenteric vasoconstriction. After endothelial denudation, the dilator response to anandamide was slightly reduced and was no longer inhibited by SR141716A. In preparations from LPS-pretreated rats, SR141716A alone caused a significant and prolonged increase in perfusion pressure, whereas it had no such effect in control preparations perfused in vitro with or without LPS or after endothelial denudation in preparations from rats pretreated with LPS. We conclude that anandamide-induced mesenteric vasodilation is mediated by an endothelially located SR141716A-sensitive "anandamide receptor" distinct from CB1 cannabinoid receptors and that activation of such receptors by an endocannabinoid, possibly anandamide, contributes to LPS-induced mesenteric vasodilation in vivo.
Hypertension 1999 Jan
PMID:Mesenteric vasodilation mediated by endothelial anandamide receptors. 993 Nov 42

We investigated involvement of the autonomic nervous system in gastric motor and cardiovascular responses to delta9-tetrahydrocannabinol (delta9-THC) in anesthetized rats. Intravenously administered delta9-THC evoked long-lasting decreases in intragastric pressure and pyloric contractility, bradycardia, and hypotension. The changes in gastric motor function and bradycardia were abolished by vagotomy and ganglionic blockade, whereas spinal cord transection prevented the hypotensive response. Administered intravenously alone, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-met hyl-1H-pyrazole-3-carboxamide, a putative cannabinoid CB1 receptor antagonist, evoked transient decrease in intragastric pressure, and hypertension that was associated with bradycardia. However, this agent completely blocked the gastric motor and cardiovascular responses to intravenous delta9-THC. Application of delta9-THC to the dorsal surface of the medulla resulted in small and short-lasting decreases in gastric motor and cardiovascular function. We conclude that the decrease in gastric motor function and bradycardia are partially due to an action of delta9-THC in the dorsal medulla and that intact vagal nerves are required. The hypotension was mediated through sympathetic pathways. Both gastric motor and cardiovascular effects of peripherally administered delta9-THC seem to be mediated through cannabinoid CB1 receptors.
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PMID:Delta9-tetrahydrocannabinol inhibits gastric motility in the rat through cannabinoid CB1 receptors. 1035 56

Cannabinoids, including the endogenous ligand anandamide, elicit pronounced hypotension and bradycardia through the activation of CB1 cannabinoid receptors. A second endogenous cannabinoid, 2-arachidonoyl glycerol (2-AG), has been proposed to be the natural ligand of CB1 receptors. In the present study, we examined the effects of 2-AG on mean arterial pressure and heart rate in anesthetized mice and assessed the role of CB1 receptors through the use of selective cannabinoid receptor antagonists and CB1 receptor knockout (CB1(-/-)) mice. In control ICR mice, intravenous injections of 2-AG or its isomer 1-AG elicit dose-dependent hypotension and moderate tachycardia that are unaffected by the CB1 receptor antagonist SR141716A. The same dose of SR141716A (6 nmol/g IV) completely blocks the hypotensive effect and attenuates the bradycardic effect of anandamide. 2-AG elicits a similar hypotensive effect, resistant to blockade by either SR141716A or the CB2 antagonist SR144528, in both CB1(-/-) mice and their homozygous (CB1(+/+)) control littermates. In ICR mice, arachidonic acid (AA, 15 nmol/g IV) elicits hypotension and tachycardia, and indomethacin (14 nmol/g IV) inhibits the hypotensive effect of both AA and 2-AG. Synthetic 2-AG incubated with mouse blood is rapidly (<2 minutes) and completely degraded with the parallel appearance of AA, whereas anandamide is stable under the same conditions. A metabolically stable ether analogue of 2-AG causes prolonged hypotension and bradycardia in ICR mice, and both effects are completely blocked by SR141716A, whereas the same dose of 2-AG-ether does not influence blood pressure and heart rate in CB1(-/-) mice. These findings are interpreted to indicate that exogenous 2-AG is rapidly degraded in mouse blood, probably by a lipase, which masks its ability to interact with CB1 receptors. Although the observed cardiovascular effects of 2-AG probably are produced by an arachidonate metabolite through a noncannabinoid mechanism, the CB1 receptor-mediated cardiovascular effects of a stable analogue of 2-AG leaves open the possibility that endogenous 2-AG may elicit cardiovascular effects through CB1 receptors.
Hypertension 2000 Feb
PMID:Cardiovascular effects of 2-arachidonoyl glycerol in anesthetized mice. 1067 17

The present study evaluated the potential mechanism involved in the hypotensive effect induced by ET-1 in rats treated with the NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in the drinking water during 7 days. Hypertension developed in the L-NAME-treated rats (164+/-3 versus 112+/-1 mm Hg in untreated control rats), and the hypotensive effect of ET-1 (100 pmol/kg IV) was significantly enhanced compared with control rats (32+/-2% versus 20+/-1% fall in mean arterial pressure). The enhanced ET-1 hypotensive effect in L-NAME-treated rats was abolished by the ETB receptor antagonist BQ-788 but was unaltered by the cyclooxygenase inhibitor diclofenac, the cytochrome P450 inhibitor fluconazole, or the potassium channel blockers apamin, glibenclamide, tetraethylammonium, and 4-aminopyridine. Pretreatment with the cannabinoid CB1 receptor antagonist SR141716A significantly reduced the hypotensive response to ET-1 in L-NAME-treated rats (20+/-1%), although it did not modify the response in untreated control rats (17+/-1%). These findings indicate that in rats under chronic NOS inhibition, the hypotensive effect of ET-1 is unexpectedly enhanced and appears to be mediated by a non-NO/non-prostanoid mechanism and involves an SR141716A-sensitive mechanism triggered by ETB receptor activation.
Hypertension 2003 Oct
PMID:SR141716A-sensitive enhancement of ET-1 hypotensive effect by chronic NOS inhibition. 1291 62

1. The nature of the cardiorespiratory effects mediated by cannabinoids in the hindbrain is poorly understood. In the present study we investigated whether cannabinoid receptor activation in the rostral ventrolateral medulla oblongata (RVLM) affects cardiovascular and/or respiratory function. 2. Initially, we looked for evidence of CB1 receptor gene expression in rostral and caudal sections of the rat ventrolateral medulla (VLM) using reverse transcription-polymerase chain reaction. Second, the potent cannabinoid receptor agonists WIN55,212-2 (0.05, 0.5 or 5 pmol per 50 nl) and HU-210 (0.5 pmol per 50 nl) or the CB1 receptor antagonist/inverse agonist AM281 (1 pmol per 100 nl) were microinjected into the RVLM of urethane-anaesthetised, immobilised and mechanically ventilated male Sprague-Dawley rats (n=22). Changes in splanchnic nerve activity (sSNA), phrenic nerve activity (PNA), mean arterial pressure (MAP) and heart rate (HR) in response to cannabinoid administration were recorded. 3. The CB1 receptor gene was expressed throughout the VLM. Unilateral microinjection of WIN55,212-2 into the RVLM evoked short-latency, dose-dependent increases in sSNA (0.5 pmol; 175+/-8%, n=5) and MAP (0.5 pmol; 26+/-3%, n=8) and abolished PNA (0.5 pmol; duration of apnoea: 5.4+/-0.4 s, n=8), with little change in HR (P<0.005). HU-210, structurally related to Delta9-tetrahydrocannabinol (THC), evoked similar effects when microinjected into the RVLM (n=4). Surprisingly, prior microinjection of AM281 produced agonist-like effects, as well as significantly attenuated the response to subsequent injection of WIN55,212-2 (0.5 pmol, n=4). 4. The present study reveals CB1 receptor gene expression in the rat VLM and demonstrates sympathoexcitation, hypertension and respiratory inhibition in response to RVLM-administered cannabinoids. These findings suggest a novel link between CB1 receptors in this region of the hindbrain and the central cardiorespiratory effects of cannabinoids. The extent to which these central effects contribute to the cardiovascular and respiratory outcomes of cannabis use remains to be investigated.
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PMID:Cannabinoid receptor activation in the rostral ventrolateral medulla oblongata evokes cardiorespiratory effects in anaesthetised rats. 1297 95

The endocannabinoid anandamide exerts neurobehavioral, cardiovascular, and immune-regulatory effects through cannabinoid receptors (CB). Fatty acid amide hydrolase (FAAH) is an enzyme responsible for the in vivo degradation of anandamide. Recent experimental studies have suggested that targeting the endocannabinergic system by FAAH inhibitors is a promising novel approach for the treatment of anxiety, inflammation, and hypertension. In this study, we compared the cardiac performance of FAAH knockout (FAAH-/-) mice and their wild-type (FAAH+/+) littermates and analyzed the hemodynamic effects of anandamide using the Millar pressure-volume conductance catheter system. Baseline cardiovascular parameters, systolic and diastolic function at different preloads, and baroreflex sensitivity were similar in FAAH-/- and FAAH+/+ mice. FAAH-/- mice displayed increased sensitivity to anandamide-induced, CB1-mediated hypotension and decreased cardiac contractility compared with FAAH(+/+) littermates. In contrast, the hypotensive potency of synthetic CB1 agonist HU-210 and the level of expression of myocardial CB1 were similar in the two strains. The myocardial levels of anandamide and oleoylethanolamide, but not 2-arachidonylglycerol, were increased in FAAH-/- mice compared with FAAH+/+ mice. These results indicate that mice lacking FAAH have a normal hemodynamic profile, and their increased responsiveness to anandamide-induced hypotension and cardiodepression is due to the decreased degradation of anandamide rather than an increase in target organ sensitivity to CB1 agonists.
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PMID:Hemodynamic profile, responsiveness to anandamide, and baroreflex sensitivity of mice lacking fatty acid amide hydrolase. 1601 13

A cluster of risk factors associated with obesity defines the metabolic syndrome and identifies cardiometabolic risk. Accumulation of fat in the visceral depot is a more reliable predictor of cardiovascular disease than is total body mass or body mass index. The recent discovery of the endocannabinoid-CB1 receptor system and its impact on the regulation of energy metabolism represents a significant advance that will help target visceral fat and its metabolic implications. As a highly active endocrine organ, visceral fat secretes many bioactive molecules, known as adipokines. Dysregulation of these adipokines contributes to the pathogenesis of the obesity-associated metabolic syndrome, resulting in insulin resistance, type 2 diabetes, hypertension, hyperlipidemia, and vascular disease. Even modest weight reduction leads to reduced cardiometabolic risk by affecting the individual components comprising the metabolic syndrome.
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PMID:The progression of cardiovascular risk to cardiovascular disease. 1793 92

Cardio-respiratory effects of an intravenous injection of arvanil, a structural "hybrid" between capsaicin and anandamide, were investigated in 40 urethane-chloralose anaesthetized and spontaneously breathing rats. In the group of rats the response to arvanil was checked to establish the appropriate dose of the drug. To analyze the pattern of the cardio-respiratory effects rats were challenged with bolus injection of arvanil (0.8 mg kg(-1)) into the femoral vein. Administration of the drug evoked, in all tested rats, a significant increase of tidal volume (V(T)) and diaphragm activity, hypertension coupled with a fall in respiratory rate (f). To test the contribution of vanilloid (VR1) and cannabinoid (CB1) receptors to post-arvanil response, administrations of the drug were preceded by nonselective VR1 antagonist ruthenium red, selective VR1 antagonist SB366791 or selective CB1 antagonist AM281. All antagonists eliminated an increase in V(T) but failed to block the hypertension evoked by arvanil. Ruthenium red as well as SB366791 abolished post-arvanil fall in respiratory rate. The rise of diaphragm activity was totally eliminated by ruthenium red and markedly reduced by SB366791. AM281 blockade of post-arvanil changes in f and diaphragm activity was ineffective. These findings indicated that the post-arvanil rise of V(T) was mediated by both VR1 and CB1 receptors. Only vanilloid receptors were involved in the increase of diaphragm activity and decrease of respiratory frequency. Hypertensive response to arvanil might depend on different types of receptors.
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PMID:Role of VR1 and CB1 receptors in modelling of cardio-respiratory response to arvanil, an endocannabinoid and vanilloid hybrid, in rats. 1857 97

Cardiometabolic risk factors affect more than 47 million adults in the United States today. Although certain risk factors (e.g., obesity, dyslipidemia, hypertension, and hyperglycemia) contribute independently to the global risk, dyslipidemia is one of the most important risk factors for cardiovascular disease. Successful treatment requires a well-coordinated multifaceted approach, with commitment to a long-term program for disease management. Although initial attempts should focus on dietary changes and increased physical activity, most patients also need effective, safe, and well-monitored pharmacotherapy. Experimental studies have shown that overactivation of the endocannabinoid system-a physiologic signaling system involved in regulating energy intake, fatty acid synthesis and storage, and glucose and lipid metabolism-is associated with obesity, dyslipidemia, and insulin resistance. In clinical trials, selective blockade of CB1 receptors has resulted in substantial weight loss and significant improvement in lipid profiles. The effects of rimonabant, the first selective CB1 receptor blocker, were evaluated in 6600 obese or overweight adults who participated in one of 4 multicenter, placebo-controlled, randomized clinical trials for at least 1 year. Significant improvement in lipid profiles (specifically HDL and triglyceride levels and ratio of total cholesterol to HDL cholesterol) was seen in the 2503 patients taking rimonabant 20 mg/day, independent of its substantial effects on weight loss. No significant changes in LDL or total cholesterol were observed. Results of clinical trials with rimonabant are promising. Additional long-term controlled studies with appropriate follow-up are warranted to confirm the clinical potential of this drug, particularly its effects on dyslipidemia and other cardiovascular endpoints.
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PMID:The endocannabinoid system and cardiometabolic risk: effects of CB1 receptor blockade on lipid metabolism. 1871 60

Cardiovascular mortality remains the first cause of death worldwide. This high mortality rate is directly associated with the increase of cardiovascular risk factors such as: obesity, hypertension, diabetes and hypercholesterolemia. Current tight management and new pharmacological treatment of cardiovascular risk factors decrease the cardiovascular mortality rate in general population. However, insulin resistance, hypo-adiponectinemia and inflammatory factors persist and are linked with atherosclerosis. Additional therapeutic solutions are needed. Rimonabant, a CB1-blocker brings novel perspective to manage several cardiovascular risk factors. Unfortunately, Rimonabant has been withdrawn from the market. Therefore, it has not been possible to assess in long term its efficacy on cardiovascular mortality.
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PMID:[Nutrition-obesity. Rimonabant and cardiovascular risk factors]. 1921 25


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