Evidence for the Role of Nitric Oxide in the Circulation of the Dental Pulp

Abstract

Many authors have studied the hemodynamics of the dental pulp; however, there are scarcely any data regarding the involvement of the L-arginine/nitric oxide pathway in the regulatory mechanism. Thus, we have examined the physiological effects of (1) NG-nitro-L-arginine as an inhibitor of nitric oxide synthesis and (2) the nitric oxide donor 3-morpholinosydnonimine on blood flow and vascular resistance in the canines of anesthetized cats to study the potential involvement of nitric oxide in the regulation of dental vascular homeostasis. Mean arterial blood pressure, heart rate, blood gases, pH, cardiac output, and tissue blood flow were determined prior to and 15 min after i.v. administration of either NG-nitro-L-arginine (30 mg/kg, n = 9) or 3-morpholinosydnonimine (1 mg/kg, n = 7). Blood flow was measured by radioactive-labeled microspheres. There were no significant differences in baseline parameters between the two groups of cats. The dental pulp blood flow decreased to 53 +/- 13% (p < 0.01) of the control level after NG-nitro-L-arginine administration, while it decreased only slightly (to 82 +/- 12%) after 3-morpholinosydnonimine administration. The dental pulp's vascular resistance increased to 367 +/- 69% (p < 0.01) of the control level after NG-nitro-L-arginine, while it decreased to 73 +/- 10% (p < 0.05) of control after 3-morpholinosydnonimine. We found that the L-arginine/nitric oxide pathway plays an important role in the regulation of pulpal blood circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization and Changes in NADPH-Diaphorase Reactivity and Nitric Oxide Synthase Immunoreactivity in Rat Pulp Following Tooth Preparation

“…Indeed, systemic infusion of the NOS inhibitor NG-nitro-l-arginine methyl ester (L-NAME) has been shown significantly to reduce basal blood flow in the rat mandibular incisor pulp (Kerezoudis et al, 1993a) and the cat mandibular canine (Lohinai et al, 1995). Further, administration of the nitric oxide donor 3-morpholinosydnonimine (SIN-1) significantly decreased pulpal vascular resistance in the cat mandibular canine (Lohinai et al, 1995). An alternative explanation for the NADPH-d activity in pulpal vessels is the presence of nNOS in nerves which are in the vicinity of vessels ladecola et al, 1993).…”

Nitric Oxide Synthase and PGE2 Reciprocal Interactions in Rat Dental Pulp: Cholinoceptor Modulation

“…In vivo studies demonstrated that the NOdependent pathway plays an important role in regulating the basal vasodilator tone and blood circulation in dental pulp (22). Furthermore, the substance P released from the sensory nerve endings produces vasodilatation, thus inducing NO production from endothelial cells (23).…”

Neural Control of Pulpal Blood Flow

“…Thus, a basal formation of NO appears to be maintained as a consequence of the continuous enzyme activation of the endothelium, e.g., by shear stress. Support for a role of NO in regulation of vascular tone was obtained in studies on rat incisors and cat canine teeth which showed that treatment with an inhibitor of NO-synthase caused vasoconstriction (Kerezoudis et al, 1993b;Lohinai et al, 1995). Since the vascular endothelium continously generates both a vasoconstrictor substance (ET) and a vasodilator agent (NO), there are prerequisites for modulation of pulp circulation without influence of nerves.…”