Cannabidiol (CBD) is a major, nonpsychoactive Cannabis constituent with anti-inflammatory activity mediated by enhancing adenosine signaling. Inasmuch as adenosine receptors are promising pharmaceutical targets for ischemic heart diseases, we tested the effect of CBD on ischemic rat hearts. For the in vivo studies, the left anterior descending coronary artery was transiently ligated for 30 min, and the rats were treated for 7 days with CBD (5 mg/kg ip) or vehicle. Cardiac function was studied by echocardiography. Infarcts were examined morphometrically and histologically. For ex vivo evaluation, CBD was administered 24 and 1 h before the animals were killed, and hearts were harvested for physiological measurements. In vivo studies showed preservation of shortening fraction in CBD-treated animals: from 48 +/- 8 to 39 +/- 8% and from 44 +/- 5 to 32 +/- 9% in CBD-treated and control rats, respectively (n = 14, P < 0.05). Infarct size was reduced by 66% in CBD-treated animals, despite nearly identical areas at risk (9.6 +/- 3.9 and 28.2 +/- 7.0% in CBD and controls, respectively, P < 0.001) and granulation tissue proportion as assessed qualitatively. Infarcts in CBD-treated animals were associated with reduced myocardial inflammation and reduced IL-6 levels (254 +/- 22 and 2,812 +/- 500 pg/ml in CBD and control rats, respectively, P < 0.01). In isolated hearts, no significant difference in infarct size, left ventricular developed pressures during ischemia and reperfusion, or coronary flow could be detected between CBD-treated and control hearts. Our study shows that CBD induces a substantial in vivo cardioprotective effect from ischemia that is not observed ex vivo. Inasmuch as CBD has previously been administered to humans without causing side effects, it may represent a promising novel treatment for myocardial ischemia.

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SummaryC-reactive protein (CRP) is a strong predictor for acute cardiovascular events. Several endothelial prothrombotic effects of CRP have been recently reported. This study examined the effect of CRP on bovine aortic endothelial cell (EC) activation and capacity to recruit human platelets under flow conditions using the cone and plate(let) analyser method. Human recombinant CRP promoted platelet adhesion in a dose-and timedependent manner, with a maximal effect at 20 lg/ml (increase of 174% over baseline, P < 0AE01). Similar effects were observed following incubation of EC with sera of transgenic mice that express human CRP (10 lg/ml). Antiintercellular adhesion molecule-1 neutralising monoclonal antibody and nitric oxide donor, sodium nitroprusside, blocked the effect of CRP, reducing adhesion from 202% to 128% (P < 0AE05) and 114% (P ¼ 0AE02) respectively. The pro-adhesive effect of CRP was abolished by calphostin C (a protein kinase C inhibitor), whereas the extracellular signal-regulated kinase antagonist, PD98059, did not have any effect. CRP promoted P-selectin expression on the EC surface and blockade of P-selectin reversed CRPinduced platelet adhesion. In conclusion, CRP promoted platelet adhesion to EC. Our results emphasise the possible role of CRP in linking inflammation and thrombosis and provide a potential mechanism for the high incidence of vascular events associated with high CRP levels.Keywords: C-reactive protein, platelets, endothelium, adhesion, cone and platelet analyser. Materials and methods Cells and reagentsBovine aortic endothelial cells (BAEC) were maintained in an incubator at 37°C, 5% CO 2 and a humidified atmosphere. Cells were grown in Dulbecco's modified Eagles medium supplemented with 10% fetal calf serum, l-glutamine and 1% penicillin-streptomycin in four-well tissue culture plates (NUNC, Rochester, NY, USA) until they reached 80% confluence, prior to being utilised in the platelet adhesion assay. The following reagents were used in the study: monoclonal antibodies (mAbs) raised against intercellular adhesion molecule-1 (ICAM-1) and P-selectin (Dako, A/S, Glostrup, Denmark), sodium nitroprusside (SNP), PD98059 and calphostin C (Calbiochem-Novabiochem Corp., San Diego, CA, USA), media and tissue culture supplements (Biological Industries, Beit Haemek, Israel). Platelet isolation and labellingThis study conformed to principles of Declaration of Helsinki. Whole fresh blood was collected from healthy, young volunteers (n ¼ 17), by venipuncture and stabilised in a vacutainer with a final concentration of 3AE8% sodium citrate. After resting for 30 min, platelet-rich plasma was prepared by centrifugation at 165 g for 12 min and transferred to a separate test tube. The platelets were labelled by incubation with calcein-AM (30 min, room temperature; Molecular Probes, Eugene, OR, USA), after which they were reconstituted with autologous packed cells immediately prior to the cone and platelet analyser (CPA) assay. Platelet adhesion assayPlatelet adhesion to EC under physiological shear...

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C-reactive protein (CRP) is a risk marker and a potential modulator of vascular disease. Whether CRP modulates nitric oxide (NO) synthase (NOS) activity and NO metabolism remains unclear. We studied the effect of CRP on NO metabolism in transgenic mice that express human CRP (CRPtg). CRPtg and wild-type mice were subjected to controlled femoral artery wire injury. CRP serum levels at baseline and 6 and 24 h after injury were 12.4 +/- 9, 18.6 +/- 6.9, and 58.4 +/- 13 mg/l, respectively, in CRPtg mice but were undetectable at all time points in wild-type mice. Endothelial NOS protein and mRNA expression were significantly suppressed in the injured arteries of CRPtg mice (n = 5, P< 0.05). A similar reduction in eNOS expression was observed in the distant lung and heart. NO release after injury was significantly lower in CRPtg mice, as measured by nitrate and nitrite breakdown products, with a concomitant suppression of cGMP NO signaling after injury. Endothelial NOS and NO expression after vascular injury are locally and systemically suppressed in mice that express human CRP. These in vivo observations support the hypothesis that CRP modulates NO metabolism and may have implications regarding the mechanisms by which CRP modulates vascular disease.