Iodoantipyrine and Rb⁸⁶ Cl uptake by brain, cord, and sciatic nerve in the rat

Abstract

Rb86 and Iodo131 antipyrine were injected together by vein in rats. The brain, spinal cord, and nerve contents of each label were measured 30 or 60 sec later. Iodoantipyrine values were used to calculate blood flow to these portions of the nervous system. The ratio of Rb86 to iodoantipyrine uptake was used as an index of the efficacy of the hematoneural barrier. The barrier is most complete in the brain, less complete in the spinal cord, and absent in peripheral nerve. Blood flow values per gram are: brain .41 ml/g min; cord .28 ml/g min, and nerve .11 ml/g min. It is suggested that the blood-brain barrier is an anatomical entity rather than a functional one.

Effects of changes of blood pressure, respiratory acidosis and hypoxia on blood flow in the sciatic nerve of the rat.

“…When we included the fast component in computation of blood flow, we obtained a mean value of 25-9 + 2-6 ml min-100 g-1 which is still much lower than the value obtained by these investigators for the cat sciatic nerve. Mandel et al (1963), Myers et al (1982 and Sladky et al (1983) measured blood flow in the sciatic nerves of anaesthetized rats using the [14C]iodoantipyrine distribution method and obtained mean values of 11, 14-8 and 12-1 ml min-100 g'1 which are similar to our mean value of 15-8. Tschetter, Klassen, Resch & Meyer (1970) obtained a value of 14 ml min-100 g'1 for blood flow in the vagus nerve of the dog using the distribution of labelled microspheres.…”

“…The decision to calculate flow in this way is supported by the finding that the mean flow in those nerves with mono-exponential curves was similar to that of the slow component of those with bi-exponential curves. Furthermore, the mean blood flow computed from the slow component of the seventeen bi-exponential curves was 14-5 + 0-7 ml min-m 100 g-1 which corresponds 520 BLOOD FLOW IN THE SCIATIC NERVE OF THE RAT closely to the mean values of 11-14'8 ml min' 100 g-1 obtained in the sciatic nerve of the rat by other investigators using different techniques (Mandel, Arcidiacono & Sapirstein, 1963;Myers, Mizisin, Powell & Lampert, 1982;Sladky, Greenberg & Brown, 1983). By contrast, nerve blood flow computed by taking into account both fast and slow components (25-9 + 2-6 ml min' 100 g-1) is approximately 70 % higher than the values obtained by the investigators cited above.…”

Vascular Physiology and Protein Disposition in a Preclinical Model of Neurodegeneration

“…The relative rates of blood flow in brain and other tissues were determined by sacrificing mice exactly 90 s after an intravenous bolus injection of a 185 kBq quantity of two distinct blood flow markers: 99m Tc-HMPAO, which crosses the blood–brain barrier, and 86 RbCl, which is excluded by the blood–brain barrier. − The utility of 99m Tc-HMPAO, a small, lipophilic metal–ligand complex, as an indicator of cerebral blood flow is well established; − however, it has also been used to measure tumor blood flow rates . Cationic rubidium radioprobes (e.g., 81 Rb + , 82 Rb + , 86 Rb + ) are polar analogues of monocationic potassium (K + ) that have been successfully utilized as tumor perfusion agents ,,,− and as markers of blood–brain barrier integrity due to their selective permeability only through K + transporters at a slow, steady rate. − After euthanasia by cervical dislocation under isoflurane anesthesia, tissue samples were promptly collected and counted for radioactivity in the appropriate gamma energy window. The percentage of injected 99m Tc-HMPAO or 86 Rb + dose per gram of tissue (% ID/g) was computed and may be considered to be proportional to the rate of blood flow.…”