Biomedical subjects

G C Yun

Publications and source records attributed to G C Yun.

3 recordsLinked to original sources

PubMed1988

Renotropic stimulation in rat kidney cell culture.

A circulating renotropic factor specific for renal cells has been described in rats. The addition of sera obtained from unilaterally nephrectomized (uni) rats 24h after operation compared to sham-operated (sham) rats augments 3H-thymidine incorporation into the DNA of incubating kidney slices approximately 10%-30%. Attempting to amplify the sensitivity of the assay for this renotropic agent, we replaced slices with primary rat kidney cultures. The assay system was based on one previously used for rabbits. The cultured cells were synchronized in their growth phase by a period of protein-free starvation. Compared to sera from sham rats, sera from uni rats showed significant stimulation of thymidine incorporation into DNA, 35.5% +/- 9.3 (SEM), p less than .0001, at 16 h; 63.3% +/- 10.0 (SEM), p less than .001, at 24 h; and 19.5% +/- 6.5 (SEM), p less than .01, at 48 h post operation. Accordingly, the maximal stimulation at 24 h was greater than that previously found using the kidney slice assay. Measurable renotropic activity occurred earlier and over a shorter duration than in rabbits. Stimulation was similar when a D-valine medium, relatively specific for renal epithelial cells, replaced DME medium. We conclude that growth synchronized, primary rat renal cells in culture verify the presence of a circulating renotropin arising 24 h post uni.

Animals↗

PubMed1988

The rabbit renotropic system.

Elevated levels of a specific renal growth factor, renotropin, have been associated with spontaneous hypertension. To examine this association more closely, we have undertaken the development of a better assay system to characterize and purify renotropin. Sera from rabbits prior to operation (control) and at a specified time after unilateral nephrectomy (uni) were examined for renotropic activity. Comparing the effects of uni to control sera in the same rabbit, significant stimulation of 3H-thymidine incorporation into the DNA of primary rabbit kidney cultures incubated in D-valine medium to eliminate fibroblast growth was noted: at 3 days postoperatively 73% (n = 13), at 7 days 103% (n = 39), at 10 days 130% (n = 31), at 21 days 101% (n = 24), at 42 days 89% (n = 13). All values were at least P less than 0.01. The stimulatory properties were dose-dependent but reached a plateau at high serum concentrations. Comparing CPM/mg protein in uni/control in different concentrations of sera 7 days postoperatively, uni versus control were 67/44 at 5% v/v, 139/72 at 10% v/v, 261/161 at 20% v/v, and 243/136 at 40% v/v. The renotropic effect of uni sera remained after dialysis in incubation medium and after sera were heated in boiling water for 5 minutes. Renal extracts obtained from growing kidneys 7 days postnephrectomy augmented renotropic activity. Atrial natriuretic factor, ouabain, PGF2 alpha, PGE1, and cAMP did not possess renotropic activity. We conclude that the primary rabbit kidney culture assay for renotropin is highly sensitive and will be an important tool to comprehend the role of renotropin in the pathogenesis of hypertension.

Animals↗

PubMed1987

Effects of sera from uninephrectomized rats on renal slices: PAH and TEA uptake and QO2.

We followed the effects of sera from unilaterally nephrectomized (uninephectomized) rats compared to sham-operated rats on 3H-p-aminohippurate (3H-PAH) and 14C-tetraethylammonium (14C-TEA) uptake and oxygen consumption (QO2) in incubating rat kidney slices. These studies were based on the assumption that a circulating renotropic substance might also influence various transport mechanisms. Sera were obtained at various times postoperation; the height of renotropic activity occurs 17-24 h after kidney extirpation. Sera removed 17-24 h postuninephrectomy significantly decreased both 3H-PAH and 14C-TEA uptake in incubating kidney slices. Similar to the inability to show significant renotropic activity after 36 h, sera obtained 48, 96, and 168 h postuninephrectomy had no significant influence on 3H-PAH and 14C-TEA uptake. Addition of sera (10% v/v) generally depressed QO2. However, sera obtained from uninephrectomized rats compared to sera from sham-operated rats had relatively more depressive effects on QO2 in renal tissue after 30 min of incubation (p less than 0.01). No significant differences in QO2 were seen when the uninephrectomized and sham-operated sera were added to the tissue immediately or after 60 min of incubation in the sera. These serum studies on 3H-PAH and 14C-TEA uptake simulate in many respects ones performed previously with serum from spontaneously hypertensive and salt-loaded rats and suggest the presence of a common circulating factor.

Aminohippuric Acids↗