Effects of hydroalcoholic extracts of Portulaca pilosa and Achyrocline satureioides on urinary sodium and potassium excretion.

Porulaca pilosa has been used in Brazil as a traditional remedy to cause diuresis, antipyresis and analgesia. Achyrocline satureioides has been used in folk medicine as antiinflammatory, hypoglycemic, sedative and to treat gastrointestinal disorders such as diarrhea and dysentery suggesting that it may affect salt and water reabsorption by the gastrointestinal tract. In the current study, hydroalcoholic extracts of both plants were investigated in order to examine their renal effects. The results support the claim that extracts of P. pilosa present renal effects but not the popular belief that it affects diuresis. It has also been provided that, in rats, it causes an increase in K excretion without a concomitant change in water diuresis or Na excretion. Our findings also support the popular belief that A. satureioides does not apparently have renal effects and it might change renal ion transport based on observations that it affects gastrointestinal reabsorption.

ATP-sensitive potassium channels do not mediate vasorelaxation by acetylcholine or iloprost.

The influence of glibenclamide (GBC), a blocker of ATP-sensitive K+ channels, on relaxation caused by cromakalim (CKL), acetylcholine (ACh) and iloprost (ILO) was assessed in aortic rings (AR) with (E+) or without endothelium (E-) and in the perfused arterial mesentery (MES) of the rat. In AR preconstricted with noradrenaline, CKL (0.03-10 microM) and ILO (5.5 nM-1.6 microM) caused graded vasodilations which were not modified by endothelium removal. ACh (0.01-3 microM) only relaxed E+AR preparations. GBC (3 microM) markedly reduced responses to CKL in E+AR and E-AR, but did not affect vasodilation induced by ILO in E+AR or E-AR and by ACh in E+AR. In MES preconstricted with methoxamine, bolus injections of CKL (10 or 30 nmol) or ACh (0.03-1 nmol) caused graded reductions of perfusion pressure. Only the responses to CKL were significantly inhibited by GBC (10 microM). We conclude that AR and MES contain functional ATP-sensitive K+ channels, which, however, do not play a significant role in the endothelium-dependent vasodilation triggered by ACh or in the endothelium-independent relaxation induced by ILO.

ATP-sensitive potassium channels do not mediate vasorelaxation by acetylcholine or iloprost

The influence of glibenclamide(GBC), a blocker of ATP-sensitive K+ channells, on relaxation caused by cromakalin(CKL), acetylcholine (ACh) and iloprost (ILO) was assessed in aortic rings (AR) with (E+) or without endotheliium (E-) and in the perfused arterial mesentery (MES) of the rat. In AR preconstricted with noradrenaline, CKL(0.03-10 *M) and ILO (5.5 nM) caused graded vasodilations which were not modified by endothelium removal. ACh(0.01-3 *M) only relaxed E+AR preparations. GBC (3*M) markedly reduced responses to CKL in E+AR and E-AR, but did not affect vasodilation induceds by ILO in E-AR and by ACH in E+AR. In MES preconstricted with methoxamine, bolus injections of CKL (10 or 30 nmol) or ACh (0.03-1nmol) caused graded reductions of perfusion pressure. Only the responses to CKL were significantly inhibited by GBC (10 *M). We conclude that AR and MES contain functional ATP-sensitive K+ channels, which, however, do not play a significant role in the endothelium-dependent vasodilation triggered by ACh or in the endothelium-indipendent relaxation induced by ILO