Dianna E. Van Orden

Furosemide induced release of prostaglandin E to increase renal blood flow.

Summary Levels of PGE in renal venous blood were found to be significantly elevated at the time RBF was increased by furosemide. Following indomethacin, a second dose of furosemide failed to increase RBF and levels of PGE in renal venous blood were not elevated. Levels of PGF and PGA were not affected by furosemide. The increase of PGE in renal venous blood at the time of renal dilation supports the hypothesis that furosemide increases RBF by releasing PGE. An intrarenal action of the released PGE is implied by this mechanism.

Ethacrynic acid induced release of prostaglandin E to increase renal blood flow.

Ethacrynic acid administered to anesthetized dogs was found to increase the level of prostaglandin E as determined by radioimmunoassay in renal venous blood at the time when renal blood flow was increased by this agent. No change was found in the renal venous level of prostaglandin F. When ethacrynic acid was administered after treatment with indomethacin, which blocks the increase in renal blood flow induced by the natriuretic agent, no increase in the renal venous level of prostaglandin E was seen. Thus, the dilation of the renal vasculature would appear to be caused by a stimulation of synthesis and release of prostaglandin E by ethacrynic acid.

Role of endogenous prostaglandins in regulation of uterine blood flow and adrenergic neurotransmission

Earlier studies from these laboratories have demonstrated that prostaglandins (PGs) of the A and E series are potent uterine vasodilators whereas PGFs do not significantly alter uterine vascular resistance. In addition, PGEs and PGFs are also able to modify adrenergic vasoconstrictor responses in the canine uterus. In the present study the role of endogenous prostaglandins in regulating uterine vascular resistance and adrenergic neurotransmission was evaluated. Intra-arterial infusion of the prostaglandin synthesis inhibitor meclofenamate resulted in a significant reduction in PGE levels in uterine venous plasma and increased vascular resistance. Uterine vasoconstrictor responses produced by sympathetic nerve stimulation and norepinephrine were enhanced when endogenous PG synthesis was inhibited. During sympathetic nerve stimulation, uterine venous plasma levels of radioimmunoassayable prostaglandins of the E of F series did not change, suggesting that the adrenergic activation of PG synthesis is not detectable in uterine venous efferent. These data suggest that endogenous prostaglandins of the E series appear to play an important role in regulating uterine blood flow (I) by relaxing uterine vascular smooth muscle and (2) by depressing adrenergic vasoconstrictor responses.

The Analysis and Fractionation of LH125I by Gel Filtration

SummaryGel filtration can be used to fractionate LH125I into three components: aggregate, monomer, and subunit. Only the monomer has satisfactory immunoreactivity. The plot of logit 100 B/Bo vs nanograms unlabeled hormone is linear over the range of the standard curve. The slope deviated from the theoretical value of —2.303, probably because of the use of an excess amount of specific antiserum. The high resolution gel filtration used provides an assessment of the quality of the LH125I on the day of preparation, and can also be used over a period of 7-8 weeks to isolate sufficient immunoreactive monomer from the heterogeneous stock solution to perform radioimmunoassays.Summary Gel filtration can be used to fractionate LH125I into three components: aggregate, monomer, and subunit. Only the monomer has satisfactory immunoreactivity. The plot of logit 100 B/B o vs nanograms unlabeled hormone is linear over the range of the standard curve. The slope deviated from the theoretical value of —2.303, probably because of the use of an excess amount of specific antiserum. The high resolution gel filtration used provides an assessment of the quality of the LH125I on the day of preparation, and can also be used over a period of 7-8 weeks to isolate sufficient immunoreactive monomer from the heterogeneous stock solution to perform radioimmunoassays.