Identification and characterization of novel perivascular adventitial cells in the whole mount mesenteric branch artery using immunofluorescent staining and scanning confocal microscopy imaging.

A novel perivascular adventitial cell termed, adventitial neuronal somata (ANNIES) expressing the neural cell adhesion molecule (NCAM) and the vasodilator neuropeptide, calcitonin gene-related peptide (CGRP), exists in the adult rat mesenteric branch artery (MBA) in situ. In addition, we have previously shown that ANNIES coexpress CGRP and NCAM. We now show that ANNIES express the neurite growth marker, growth associated protein-43(Gap-43), palladin, and the calcium sensing receptor (CaSR), that senses changes in extracellular Ca(2+) and participates in vasodilator mechanisms.

Psychosocial factors contribute to resting blood pressure in African Americans.

Objectives: African Americans as a group have higher blood pressure than individuals of northern European ancestry (non-Hispanic Whites). We investigate whether psychosocial factors explain the resting blood pressure of healthy, community-dwelling African Americans in our study.

Participants: A convenience sample of self-reported normotensive African Americans aged 18-65 years who live in the North Carolina Triangle region.

Action of thiazide on renal interstitial calcium.

Background: Although thiazides increase urinary sodium excretion, they also decrease urinary calcium excretion. Recent studies in our laboratory have shown that increased dietary salt significantly reduces interstitial fluid calcium in Dahl salt-sensitive (DS) rats, and this was associated with a rise in blood pressure and increased urinary calcium excretion. Owing to the vasorelaxant actions of increased extracellular fluid calcium, we reasoned that the antihypertensive action of hydrochlorothiazide (HCTZ), a commonly used thiazide, may be the result of increased interstitial fluid calcium as a consequence of decreased urinary calcium excretion.

Cytochrome P-450 metabolites of 2-arachidonoylglycerol play a role in Ca2+-induced relaxation of rat mesenteric arteries.

The perivascular sensory nerve (PvN) Ca(2+)-sensing receptor (CaR) is implicated in Ca(2+)-induced relaxation of isolated, phenylephrine (PE)-contracted mesenteric arteries, which involves the vascular endogenous cannabinoid system. We determined the effect of inhibition of diacylglycerol (DAG) lipase (DAGL), phospholipase A(2) (PLA(2)), and cytochrome P-450 (CYP) on Ca(2+)-induced relaxation of PE-contracted rat mesenteric arteries. Our findings indicate that Ca(2+)-induced vasorelaxation is not dependent on the endothelium.

Identification of a Ca2+-sensing receptor in rat trigeminal ganglia, sensory axons, and tooth dental pulp.

Extracellular Ca2+ regulates dentin formation, but little information is available on this regulatory mechanism. We have previously reported that sensory denervation reduces dentin formation, suggesting a role for sensory nerves in tooth mineralization. The G protein-coupled Ca2+-sensing receptor (CaR) is expressed in dorsal root ganglia and perivascular sensory nerves in mesenteric arterioles, and activation of these receptors by Ca2+ has been shown to induce vascular relaxation.

Ca(2+) mobilization through dorsal root ganglion Ca(2+)-sensing receptor stably expressed in HEK293 cells.

The rat dorsal root ganglion (DRG) Ca(2+)-sensing receptor (CaR) was stably expressed in-frame as an enhanced green fluorescent protein (EGFP) fusion protein in human embryonic kidney (HEK)293 cells, and is functionally linked to changes in intracellular Ca(2+) concentration ([Ca(2+)](i)). RT-PCR analysis indicated the presence of the message for the DRG CaR cDNA. Western blot analysis of membrane proteins showed a doublet of 168-175 and 185 kDa, consistent with immature and mature forms of the CaR.

Adventitial neuronal somata.

Confocal analysis of the whole-mount rat mesenteric branch arteries (MBA) revealed nucleated structures with axonal processes which immunostained for calcitonin gene-related peptide (CGRP). Immunocytochemistry ruled out the possibility that these were immune elements (macrophages and mast or dendritic cells) in close proximity with nerve fibers. To test our hypothesis that beta-CGRP is expressed in the rat MBA, we performed RT-PCR using total RNA isolated from the mesenteric artery arcade and intron spanning primers designed to amplify 188 bp of the beta-CGRP and 333 bp of alpha-CGRP cDNA.

Endocannabinoids acting at cannabinoid-1 receptors regulate cardiovascular function in hypertension.

Background: Endocannabinoids are novel lipid mediators with hypotensive and cardiodepressor activity. Here, we examined the possible role of the endocannabinergic system in cardiovascular regulation in hypertension.

Methods And Results: In spontaneously hypertensive rats (SHR), cannabinoid-1 receptor (CB1) antagonists increase blood pressure and left ventricular contractile performance.

Renal interstitial Ca2+ during sodium loading of normotensive and Dahl-salt hypertensive rats.

It is now established that cells in many tissues including renal epithelial cells and perivascular sensory nerves have mechanisms that monitor and respond to the concentration of Ca2+ in the interstitial compartment [Ca2+(ISF)]. We tested the hypothesis that high Na+ intake alters renal [Ca2+(ISF)] and that the response is altered in salt-sensitive hypertensive versus normotensive rats. Male Wistar (W), Dahl salt-resistant (DR), and Dahl salt-sensitive (DS) rats were fed diets containing 0.

Molecular cloning and characterization of a rat sensory nerve Ca2+-sensing receptor.

A full-length cDNA encoding a Ca2+-sensing receptor (CaSR) expressed in rat dorsal root ganglia (DRG) was identified using rapid amplification of 5'-cDNA ends and primer extension and then cloned into the plasmid vector pCR3.1. The DNA sequence of the DRG CaSR was 99.

Selective ligands and cellular effectors of a G protein-coupled endothelial cannabinoid receptor.

The cannabinoid analog abnormal cannabidiol [abn-cbd; (-)-4-(3-3,4-trans-p-menthadien-[1,8]-yl)-olivetol] does not bind to CB(1) or CB(2) receptors, yet it acts as a full agonist in relaxing rat isolated mesenteric artery segments. Vasorelaxation by abn-cbd is endothelium-dependent, pertussis toxin-sensitive, and is inhibited by the BK(Ca) channel inhibitor charybdotoxin, but not by the nitric-oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester or by the vanilloid VR1 receptor antagonist capsazepine. The cannabidiol analog O-1918 does not bind to CB(1) or CB(2) receptors and does not cause vasorelaxation at concentrations up to 30 microM, but it does cause concentration-dependent (1-30 microM) inhibition of the vasorelaxant effects of abn-cbd and anandamide.

Normal perivascular sensory dilator nerve function in arteries of Zucker diabetic fatty rats.

Background: Type II diabetes in humans is associated with pathology of both the cardiovascular and peripheral sensory nervous systems. Because abnormal vasodilator responses have been reported in animals of type II diabetes and perivascular sensory nerves are a source of vasodilator substances, we tested the hypothesis that sensory nerve-dependent relaxation is abnormal in arteries of the Zucker diabetic fatty (ZDF) rat model of type II diabetes.

Methods: The ZDF rats and genetic controls were studied at 26 weeks of age.

CB(1) receptor antagonist SR141716A inhibits Ca(2+)-induced relaxation in CB(1) receptor-deficient mice.

Mesenteric branch arteries isolated from cannabinoid type 1 receptor knockout (CB(1)(-/-)) mice, their wild-type littermates (CB(1)(+/+) mice), and C57BL/J wild-type mice were studied to test the hypothesis that murine arteries undergo high sensitivity Ca(2+)-induced relaxation that is CB(1) receptor dependent. Confocal microscope analysis of mesenteric branch arteries from wild-type mice showed the presence of Ca(2+) receptor-positive periadventitial nerves. Arterial segments of C57 control mice mounted on wire myographs contracted in response to 5 micromol/L norepinephrine and responded to the cumulative addition of extracellular Ca(2+) with a concentration-dependent relaxation that reached a maximum of 72.