PubMed · 4387516
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R F Muther. 1968. Antihistamines.. https://doi.org/10.1097/00004311-196806010-00026
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We have previously found that oral or intravenous administration of PC-2, a polysaccharide fraction purified from extracts of lichen Flavoparmelia caperata, facilitates the induction of long-term potentiation (LTP) in the dentate gyrus of anesthetized rats. PC-2 could be useful in the development of therapeutic drugs for senile dementia. However, it has been very difficult to obtain the material Flavoparmelia caperata because of its scarcity. In the present study, we therefore investigated whether PB-2, a polysaccharide fraction from another lichen Flavoparmelia baltimorensis, has similar biological effects. Oral administration of PB-2 (100-200 mg/kg) did not affect basal evoked potentials, but significantly promoted the induction of LTP following tetanic stimulation (30 pulses at 60 Hz) in the dentate gyrus of anesthetized rats. Intravenous injection of PB-2 (1-5 mg/kg) was also effective in promoting the induction of LTP, but intracerebroventricular injection of PB-2 (1-2 mg/brain) was ineffective. PB-2, as well as PC-2, should be valuable in identifying factors that promote synaptic plasticity in the hippocampus.
The administration of extracellular, hemoglobin-based oxygen carriers often elicits an acute increase in blood pressure by vasoconstriction. This side effect is now recognized to be due to the depletion of nitric oxide (endothelial-derived relaxing factor) by the extravasuated hemoglobins. We have recently found that the administration of a recombinant human serum albumin (rHSA)-based oxygen carrier involving synthetic tetraphenyporphinatoiron(II) derivative (FeP) (rHSA-FeP) does not induce such hypertensive action, because of its low permeability through the vascular endothelium. The heart rate responses after the rHSA-FeP injection were also negligibly small. Visualization of the intestinal microcirculatory changes clearly revealed the widths of the venule and arteriole to be fairly constant. The entirely synthetic rHSA-FeP becomes a promising material as a new type of red blood cell substitute.
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