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A Fujimori

Publications and source records attributed to A Fujimori.

At least 109 records · Page 6Linked to original sources
PubMed1993

Arginine-vasopressin increases the release of ET-1 into perfusate of rat mesenteric artery.

The regulatory systems of endogenous endothelin-1 (ET-1) production from intact tissues and the effects of produced ET-1 on vascular tonus by a closed circuit perfusion system of rat mesenteric artery were investigated. It was demonstrated that ET-1 is released from intact mesenteric arterial beds from Wistar rats both under basal conditions and after stimulation with arginine-vasopressin (AVP) (10(-10)-10(-9) M). Furthermore, AVP (10(-10)-10(-9) M) markedly and dose-dependently induced the expression of prepro ET-1 mRNA in the mesenteric arterial beds. Increased release of ET-1 by AVP may contribute to maintaining vascular tonus. Concomitant addition of actinomycin D inhibited the increased expression of prepro ET-1 mRNA and reduced the amount of immunoreactive ET-1 found during the 6-hour perfusate from AVP (10(-10) M)-stimulated and -unstimulated tissues.

Animals↗
PubMed1993

Desensitization of calcium messenger system in parathyroid hormone-stimulated opossum kidney cells.

We have studied the desensitization of the calcium message system to parathyroid hormone (PTH) by monitoring intracellular calcium concentration ([Ca2+]i) in an opossum kidney cell line (OKP). PTH (10(-7) M) caused a transient increase in [Ca2+]i, with an average peak height of 48.7 +/- 4.7% above baseline (n = 32). Cells stimulated with either 10(-7) or 10(-8) M PTH did not respond to a second challenge with a maximal dose (10(-7) M) of the hormone, whereas lower concentrations of PTH (10(-9) M and 10(-10) M) only partially desensitized the cells, since a [Ca2+]i transient of smaller amplitude (12.7 +/- 2.1 and 40.6 +/- 6.2% above baseline, respectively) was observed with a second stimulation. Desensitization developed within 5 min of initial hormone exposure, when PTH receptor binding was not significantly decreased. Maximal reduction of PTH binding sites (37.0 +/- 1.4%) was achieved only after 2 h. Partial desensitization was reproduced by 10(-9) M phorbol 12-myristate 13-acetate (PMA) but not by dibutyryladenosine 3',5'-cyclic monophosphate, and it was blocked by staurosporine. However, staurosporine had no effect on the complete desensitization induced by high doses of PTH. At 10(-9) M, PTH also caused a time-dependent desensitization of the adenosine 3',5'-cyclic monophosphate (cAMP) response, with maximal inhibition achieved after 2 h. PMA also decreased the cAMP response to PTH, but its inhibitory effect was less potent than that of 10(-9) M PTH. Therefore PTH induces a dose-dependent homologous desensitization of the Ca2+ message system in OKP cells, independent of receptor occupancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaloids↗