We undertook these studies to determine whether a deficient nitric oxide production in genetically hypertensive rats could result from its being scavenged by an excess production of superoxide. In one study we used a porphyrinic microsensor to measure nitric oxide concentrations released by cultured endothelial cells from stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar-Kyoto rats (WKY). SHRSP cells released only about one third the concentration of nitric oxide as did WKY cells. Treatment of cells with superoxide dismutase increased nitric oxide release, demonstrating that normally nitric oxide is scavenged by endogenous superoxide. The increase in nitric oxide release in response to superoxide dismutase treatment was more than twice as great from SHRSP as from WKY cells, demonstrating the greater amount of superoxide in the hypertensive rats. A direct measure of superoxide with the use of lucigenin demonstrated the presence of 68.1 +/- 7.1 and 27.4 +/- 3.5 nmol/L of this anion in SHRSP and WKY endothelial cells, respectively. The presence of superoxide in the rat aorta was also estimated by quantification of its effect on carbachol relaxation. This relaxation was diminished when endogenous superoxide dismutase was blocked by diethyldithiocarbamic acid. This blockade reduced the relaxation by 51.2 +/- 5.2% in SHRSP aortas and by only 22.0 +/- 8.2% (P = .015) in WKY aortas. Data from these diverse systems are in agreement that superoxide production is excessive in SHRSP tissues. This excess superoxide, by scavenging endothelial nitric oxide, could contribute to the increased vascular smooth muscle contraction and hence to the elevated total peripheral resistance of these rats.

Nitric oxide (NO) has been implicated in endogenous control of myocardial contractility. However, NO release has not yet been demonstrated in cardiac myocytes. Accordingly, endogenous NO production was measured with a porphyrinic microsensor positioned on the surface of individual neonatal or adult rat ventricular myocytes ( n > 6 neonatal and adult cells per experiment). In beating neonatal myocytes, there was no detectable spontaneous NO release with each contraction. However, norepinephrine (NE; 0.25–1 μM) elicited transient NO release from beating neonatal (149 ± 11 to 767 ± 83 nM NO) and noncontracting adult (157 ± 13 to 791 ± 89 nM NO) cells. NO was released by adrenergic agonists with the following rank order of potency: isoproterenol (β1β2) > NE (α/β1) > dobutamine (β1) ≈ epinephrine (α/β1β2) > tertbutylene (β2); NO was not released by phenylephrine (α). NE-evoked NO release was reversibly blocked by N G-monomethyl-l-arginine, trifluoperazine, guanosine 5′- O-(2-thiodiphosphate), and nifedipine but was enhanced by 3-isobutyl-1-methylxanthine (0.5 mM = 14.5 ± 1.6%) and BAY K 8644 (10 μM = 11.9 ± 1%). NO was also released by A-23187 (10 μM = 884 ± 88 nM NO), guanosine 5′- O-(3-thiotriphosphate) (1 μM = 334 ± 56 nM NO), and dibutyryl adenosine 3′,5′-cyclic monophosphate (10–100 μM = 35 ± 9 to 284 ± 49 nM NO) but not by ATP, bradykinin, carbachol, 8-bromoguanosine 3′,5′-cyclic monophosphate, or shear stress. This first functional demonstration of a constitutive NO synthase in cardiac myocytes suggests its regulation by a β-adrenergic signaling pathway and may provide a novel mechanism for the coronary artery vasodilatation and enhanced diastolic relaxation observed with adrenergic stimulation.

The aim of this study was to determine the periodontal healing of replanted dogs' teeth which, after extended extra-oral dry times, had been soaked in various media before replantation. Incisors and premolars of beagle dogs were root canal treated, extracted and bench dried. The teeth were grouped according to dry times of 30, 45 and 60 minutes. Each group of teeth was soaked in one of three media, Hank's balanced salt solution, ViaSpan (Belzer UW-CSS, Dupont Pharmaceuticals), or Conditioned Medium (supernatant of confluent culture of human gingival fibroblasts) for 30 minutes before replantation. Controls consisted of teeth extracted and replanted without drying on soaking (negative control), and bench-dried teeth replanted without soaking in the media (positive control). The dogs were killed 6 months after replantation of the teeth, which were prepared for histologic evaluation. Five microns cross-sections (every 70 microns) of the root and surrounding tissue were evaluated for healing/resorption according to Andreasen's criteria. The best healing occurred for the roots which had been immediately replanted. Healing in the positive control groups decreased with increased dry time. For the 30-minute dry time groups, soaking in media had no beneficial effect on periodontal healing compared with the controls. Soaking in ViaSpan resulted in an increased healing incidence for both the 45- and 60-minute bench-dried groups while soaking in the other media had no consistent beneficial effect. It appears from this study that an avulsed tooth that has been left dry for 30 minutes should be replanted immediately without soaking. However, teeth that have been dry for 45 or 60 minutes would benefit from soaking for 30 minutes in ViaSpan.

A previous study evaluated the viability of dog periodontal ligament cells as indicated by tritiated thymidine uptake after extended storage in Hank's balanced salt solution and Conditioned Medium. The purpose of this study was to evaluate histologic healing following the identical storage parameters established in the earlier study. Additionally, for Conditioned Medium, matched pairs (teeth evaluated for tritiated thymidine uptake and transplanted teeth) were examined in an attempt to correlate periodontal ligament vitality and healing. Forty-six extracted endodontically treated dogs' teeth were randomly grouped and stored in Hank's balanced salt solution or Conditioned Medium for 6, 48, and 96 h and then transplanted into 6-, 48-, and 96-h sockets. The control group teeth were transplanted without storage into 6-, 48-, or 96-h sockets. After 6 months the dogs were killed and the teeth were prepared for histologic evaluation according to Andreasen. Complete healing, inflammatory root resorption, and replacement resorption were evaluated and compared. Overall, significantly better healing was observed for teeth stored in Conditioned Medium than for teeth stored in Hank's balanced salt solution. Conditioned Medium was not significantly different from controls. Additionally, there was a positive correlation between periodontal ligament viability and healing for Conditioned Medium. These results confirmed the importance of periodontal ligament viability in successful replantation and the potential of Conditioned Medium as a storage medium for avulsed teeth.

Infection of the pulp space in addition to the attachment damage of a traumatic injury to a tooth, results in serious complications and often tooth loss. Therefore, the prevention or treatment of root canal infection is a major consideration in these cases. In immature teeth, revascularization of a necrotic pulp is possible and highly desirable. Unfortunately, current sensitivity tests are poor indicators of revascularization, with the result that many pulps are removed unnecessarily. Laser Doppler flowmetry is an objective test of the presence of moving red blood cells within a tissue, which has been reported to be effective in the detection of tooth pulp vitality as well. A case is presented where an eight year old child severely luxated both maxillary central incisors. While only one of the incisors was weakly responsive to CO2 ice at 76 days after replantation, the laser Doppler flowmeter indicated that revascularization was occurring in both teeth at a much earlier time. Because of the laser Doppler readings, endodontic treatment was not initiated and the teeth developed normally.