Search PubMed⌕ Search

Biomedical subjects

T Collin

Publications and source records attributed to T Collin.

24 records · Page 2Linked to original sources
PubMed1990

Ins(1,4,5)P3 formation and fluctuating chloride current response induced by external ATP in Xenopus oocytes injected with embryonic guinea pig brain mRNA.

In voltage-clamped Xenopus oocytes injected with embryonic guinea pig mRNA, effective concentrations of extracellular ATP elicited an inward fluctuating current. This current, carried by Cl-ions, was mainly dependent upon liberation of Ca2+ ions from stores as demonstrated by experiments using intracellular EGTA loading and TMB-8 superfusion. Neomycin inhibited these fluctuating currents indicating that the transplanted purinoceptor is linked to phospholipase C activity and triggers Ins(1,4,5)P3 formation. Ins(1,4,5)P3 production evoked by external ATP was clearly demonstrated by directly measuring the water-soluble Ins(1,4,5)P3 level in injected oocytes. Finally, it is suggested that the ATP effect was mediated by a Ca2+ release from Ins(1,4,5)P3 sensitive pools since heparin blocked the ATP responsiveness. The acquired purinoceptor may be made apparent to a P2 subtype since ATP and ADP were equipotent in eliciting Cl- current while AMP and Adenosine were ineffective in injected oocytes.

Adenosine↗
PubMed1988

The use of complex carbohydrates in barley groats for determination of the mouth-to-caecum transit time.

Lactulose is often used as a substrate to estimate the mouth-to-caecum transit time (MCTT), but because of osmotic effects the outcome depends on the dose consumed. In this study, barley groats, a complex carbohydrate (CH) that produces a clear breath hydrogen response after consumption, were used. Eight volunteers consumed the same dose of softened barley groats (1.0 g CH/kg body weight) three times. Ten volunteers ate three different doses (0.75, 1.0, and 1.5 g CH/kg body weight). Breath samples were collected every 30 or 60 min for at least 12.5 h and analysed for hydrogen. To study the effect of the particle size of the barley groats or the addition of fat on the MCTT, 11 volunteers consumed barley groats (1.0 g CH/kg body weight) with cream cheese (0.25 g fat/kg body weight) and 5 volunteers ate crushed barley groats (particles of +/- 1 mm, 1.0 g CH/kg body weight). After consumption of 1.0 g CH/kg body weight a mean MCTT of 8.4 +/- 0.4 h was found. After consumption of the high dose, a mean MCTT of 9.0 +/- 0.5 h was found, and after the low dose, 8.5 +/- 0.6 h. Addition of fat resulted in a significantly increased MCTT, presumably caused by retarded stomach emptying (9.2 +/- 0.6 h versus 8.1 +/- 0.5 h in controls). Particle size did not significantly affect the MCTT (7.2 +/- 0.5 h at 1 mm versus 7.8 +/- 0.6 h at normal particle size).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Investigation of human blood platelets with fluorescence spectroscopy.

Intramolecular excimer formation of dipyrenylpropane was investigated in human blood platelets. The ratio of the emission intensities of excimer to monomer (IE/IM) is sensitive to changes in lipidic membrane structure, induced by external perturbations, such as cholesteryl hemisuccinate introduction and temperature. Lack of reliable "microviscosities" determinations could be due to poor solubility of the probe in aqueous cells suspensions. Results were compared to those obtained with the fluorescence polarization technique.

Blood Platelets↗
PubMedDate not supplied

Direct vascular actions of methyclothiazide and indapamide in aorta of spontaneously hypertensive rats.

In vitro experiments were designed to assess the inhibitory effect of the thiazide diuretics methyclothiazide (MCTZ), the hydrochlorothiazide (HCTZ), and the thiazide-related diuretic indapamide (IND) on contractile responses to norepinephrine (NE) and arginine vasopressin (AVP) of aortic rings from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Changes in the tension of aortic ring preparations were measured isometrically. MCTZ (10(-4) M) induced endothelium-dependent inhibition of the vasoconstrictor responses to NE and AVP only in aortas from SHR, and the maximal vasoconstrictive effect of NE and AVP was decreased by 59 +/- 11% and 32.3 +/- 13%, respectively. Indapamide (10(-4) M) also induced endothelium-dependent inhibition of the contractile response to AVP in aortic rings from SHR, and the maximal vasoconstrictive effect of AVP was decreased by 33 +/- 5%. In contrast, HCTZ did not inhibit the contractile response to either NE or AVP, even at the highest concentration. This study provides evidence that methyclothiazide and indapamide inhibit the contractile response induced by norepinephrine and/or arginine vasopressin on SHR aortic preparations via an endothelium-dependent mechanism.

Animals↗