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To determine the relationship between the dynamics of mean arterial blood pressure (MABP) elevation and possible changes in the cochlear microcirculation the cochlear blood flow (CBF) was measured in guinea pigs by a laser Doppler method. The MABP was elevated at rates ranging from 0.02 mm Hg/s to 4 mm Hg/s by intravenous infusions of norepinephrine or epinephrine in various concentrations. A fall in MABP was induced by exsanguination of the animals. The purpose of the experiments was to record the time of onset and course of an expected autregulation in the cochlea in response to slow or rapid changes in MABP. The data suggest that there is no short-term autoregulation in the cochlear microcirculation reflecting the increase of the MABP, but a slight compensation occurs when the MABP declines. These latter changes could be attributed to the high CO sensitivity of the cochlear blood vessels. [ABSTRACT FROM AUTHOR]

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 (l 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. A nitric-oxide-dependent basal vasodilator tone exists in the dental pulp; furthermore, since the dental pulp circulation is sensitive to exogenous nitric oxide, the stimulated release of endogenous nitric oxide may also be involved in the control of the dental pulp vascular tone. [ABSTRACT FROM AUTHOR]

Copyright of Albrecht von Graefes Archiv für Klinische und Experimentelle Ophthalmologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Albrecht von Graefes Archiv für Klinische und Experimentelle Ophthalmologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Albrecht von Graefes Archiv für Klinische und Experimentelle Ophthalmologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Albrecht von Graefes Archiv für Ophthalmologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)