A Simple Cranial Window Technique for Optical Monitoring of Cerebrocortical Microcirculation and NAD/NADH Redox State. Effect of Mitochondrial Electron Transport Inhibitors and Anoxic Anoxia

Abstract

Fluorescence of NADH and vascular volume of the brain cortex of chloralose-anesthetized cats were measured by surface fluororeflectometry. A cranial window and superfusion technique was elaborated for the topical inhibition of mitochondrial electron transport in the brain cortex by amytal (inhibits at site I) and cyanide (inhibits at site III). The changes in NAD/NADH redox state and CVV evoked by these electron transport inhibitors were compared with those elicited by anoxic anoxia. Amytal (10(-3)-10(-1) M) and cyanide (10(-5)-10(-2) M) resulted in a concentration-dependent and reversible increase in cortical NAD reduction and vascular volume, but the cerebrocortical vessels were almost completely dilatated long before maximum NAD reduction was reached. Cyanide at 10(-2) M increased cortical NAD reduction and vascular volume as much as anoxic anoxia. Amytal at 10(-1) M induced approximately half of the NAD reduction evoked by 10(-2) M cyanide or anoxic anoxia, but resulted in only slightly less vasodilatation than that following cyanide and anoxic anoxia. Since amytal inhibits mitochondrial electron transport at site I--and cyanide and anoxia at site III--but induces a comparable degree of vasodilatation, it is concluded that cytochrome oxidase cannot be the single molecular oxygen sensor in the brain cortex.

Low-Frequency Oscillations of Cortical Oxidative Metabolism in Waking and Sleep

“…We should emphasize that our optical method is in principle a simplified version of the dual-wavelength technique commonly employed in NADH fluorometry (Chance et aI., 1962;Rosenthal and LaManna, 1975;Vern et aI., 1979, 198 1;Dora, 1984;Dora et aI., 1984), in con trast to the "time-sharing" methods that engage a single photodetector, more commonly utilized in cyt aa3 studies (Rosenthal et aI., 1976;10bsis et aI., 1977;Kariman and Burkhart, 1985). The stability of the PMT outputs in our experiments was continuously indicated by the degree of drift of the recorded DC voltages.…”

“…This optical method has been shown to reliably and con tinuously indicate (a) the transient oxidation of cyt aa3 following cortical stimulation under conditions of an adequate provision of oxygen and metabolic substrates (Rosenthal et aI., 1976;Jobsis et aI., 1977), (b) relative changes in cortical blood volume (Piantadosi and Jobsis-Vander Vliet, 1984), and (c) variations in the supply of either O2 or substrates (Rosenthal et aI., 1976;Brazy et aI., 1985;Jobsis Vander Vliet, 1985;Bryan and Jobsis, 1986). Whereas near-infrared transmission spectropho tometry of cortical cyt aa3 has been applied to un anesthetized animals and humans (Piantadosi and Jobsis-Vander Vliet, 1984;Brazy et aI., 1985;Jobsis-Vander Vliet, 1985), reflectance spectropho tometry in the visible light spectrum (Mitnick and Jobsis, 1976;Rosenthal et aI., 1976;Jobsis et aI., 1977;Piantadosi and Jobsis-Vander Vliet, 1984) and NADH fluorometry (Chance et aI., 1962;Rosenthal and Jobsis, 1971;Vern et aI., 1981;Dora, 1984), methods with greater spatial resolution, have been mostly utilized in anesthetized preparations. While changes in the redox state of cortical cyt aa3 and NADH are usually similar following cortical activa tion (Rosenthal and J obsis, 1971;J obsis et aI., 1977;Vern et aI., 1979;LaManna et aI., 1981;Piantadosi and Jobsis-Vander Vliet, 1984), some reported dis crepancies (Dora, 1984;Dora et aI., 1984) suggest that experimental conditions, especially the use and selection of anesthesia, may influence the obtained results, e.g., pentobarbital (Rosenthal and La Manna, 1975;Marcus et aI., 1976) versus chlo ralose (Winters and Spooner, 1966;Dora et aI., 1984).…”

“…Whereas near-infrared transmission spectropho tometry of cortical cyt aa3 has been applied to un anesthetized animals and humans (Piantadosi and Jobsis-Vander Vliet, 1984;Brazy et aI., 1985;Jobsis-Vander Vliet, 1985), reflectance spectropho tometry in the visible light spectrum (Mitnick and Jobsis, 1976;Rosenthal et aI., 1976;Jobsis et aI., 1977;Piantadosi and Jobsis-Vander Vliet, 1984) and NADH fluorometry (Chance et aI., 1962;Rosenthal and Jobsis, 1971;Vern et aI., 1981;Dora, 1984), methods with greater spatial resolution, have been mostly utilized in anesthetized preparations. While changes in the redox state of cortical cyt aa3 and NADH are usually similar following cortical activa tion (Rosenthal and J obsis, 1971;J obsis et aI., 1977;Vern et aI., 1979;LaManna et aI., 1981;Piantadosi and Jobsis-Vander Vliet, 1984), some reported dis crepancies (Dora, 1984;Dora et aI., 1984) suggest that experimental conditions, especially the use and selection of anesthesia, may influence the obtained results, e.g., pentobarbital (Rosenthal and La Manna, 1975;Marcus et aI., 1976) versus chlo ralose (Winters and Spooner, 1966;Dora et aI., 1984). In this study, attention was focused on changes in the cortical cyt aa3 redox state and blood volume during waking, slow-wave sleep, and rapid eye movement (REM) sleep.…”

Effect of the ganglioside GM1, on cerebral metabolism, microcirculation, recovery kinetics of ECoG and histology, during the recovery period following focal ischemia in cats.

“…A cranial window was fixed into the burr hole with dental cement, as described previously. 25 Electrical activity of the exposed brain cortex was measured with silver electrodes 2 mm apart built into the plastic ring of the cranial window. 23 EEG of the contralateral side was measured with copper screws fixed into the right parietal bone.…”

Effect of Iodoacetate on Local Cerebral Blood Flow and Glucose Metabolism in Cats: A Double-Radionuclide Autoradiographic Study

“…After the skin and muscle were re moved from both sides of the skull, a 12-mm-diameter hole was trefined in the left parietal bone, and the dura was carefully opened. A cranial window equipped with tubes for superfusion and a pair of small silver plates for bipolar electrocorticogram (ECoG) were then implanted into the cranial hole, as described previously (Dora and Kovach, 1983;Dora, 1984).…”