Effects of anserine on the renal sympathetic nerve activity and blood pressure in urethane-anesthetized rats.

Previous studies have demonstrated that central injection of L-carnosine (beta-alynyl-L-histidine), dipeptide synthesized in mammalian muscles, affects renal sympathetic nerve activity (RSNA) and blood pressure (BP) in anesthetized rats. In the present study, using urethane-anesthetized rats, we examined the dose-dependent effects of intravenous (IV) injection of various doses of anserine, dipeptide of similar structure to L-carnosine, on RSNA, BP and heart rate (HR). We found that injection of a low dose of anserine (1 microg) significantly suppressed RSNA, BP and HR. Conversely, a high dose (1000 microg) of anserine significantly elevated RSNA, BP and HR. Pretreatment with lateral cerebral ventricular (LCV) injection of thioperamide, a histaminergic H(3)-receptor antagonist, eliminated the effects of a low dose of anserine on RSNA, BP and HR. LCV injection of diphenhydramine, a histaminergic H(1)-receptor antagonist, abolished the effects of a high dose of anserine on RSNA, BP and HR. These findings suggest that anserine affects RSNA, BP and HR in a dose-dependent manner, and that the histaminergic nerve may be involved in the dose-different effects of anserine in rats.

Effect of temperature on cell population balance in Dexter's culture of murine bone marrow hematopoietic cells with stromal cells.

The effect of temperature in the range from 25 to 37 degrees C on the population balance of stromal and multiple-lineage hematopoietic cells from murine bone marrow at various stages of differentiation in Dexter's culture was investigated. The length of time required for stromal cells to reach confluence after inoculation of both cell types harvested from murine bone marrow was shorter at higher temperatures. On the other hand, the hematopoietic cell concentration initially decreased more rapidly at higher temperatures until the confluence of stromal cells, which should then support the proliferation of hematopoietic cells. The concentration of hematopoietic cells began to increase after 2 weeks incubation at 33 and 37 degrees C and after 4 weeks at 29 degrees C. However, the growth of hematopoietic cells was not stable at 37 degrees C, and neither stromal nor hematopoietic cells showed significant growth at 25 degrees C. The specific growth rate of hematopoietic cells at 29 degrees C after 4 weeks was comparable or higher than that at 33 degrees C, while the final concentration of hematopoietic cells was maximal at 33 degrees C. Using a cultivation method in which hematopoietic cells were recharged onto a confluent layer of stromal cells prepared at 33 degrees C, the maintenance and growth of hematopoietic cells were better at 29 degrees C than at higher temperatures. The content of progenitor cells among the hematopoietic cells increased prior to the increase in the hematopoietic cell concentration, and the progenitor cell was greater content at the lower temperature. These results suggest that cultivation at 29 degrees C might be superior to 33 degrees C for the maintenance and growth of hematopoietic cells with a prepared confluent layer of stromal cells.