Biomedical subjects

Khaled M Hazzouri

Publications and source records attributed to Khaled M Hazzouri.

3 recordsLinked to original sources

PubMed2005

Angiotensin II-induced increase of T-type Ca2+ current and decrease of L-type Ca2+ current in heart cells.

The effect of angiotensin II (Ang II) on the T- and L-type calcium currents (I(Ca)) in single ventricular heart cells of 18-week-old fetal human and 10-day-old chick embryos was studied using the whole-cell voltage clamp technique. Our results showed that in both, human and chick cardiomyocytes, Ang II (10(-7)M) increased the T-type calcium current and decreased the L-type I(Ca). The effect of Ang II on both types of currents was blocked by the AT1 peptidic antagonist, [Sar1, Ala8] Ang II (2 x 10(-7)M). Protein kinase C activator, phorbol 12,13-dibutyrate, mimicked the effect of Ang II on the T- and L-type calcium currents. These results demonstrate that in fetal human and chick embryo cardiomyocytes Ang II affects the T- and L-type Ca2+ currents differently, and this effect seems to be mediated by the PKC pathway.

Angiotensin II↗

PubMed2005

Angiotensin II induced increase in frequency of cytosolic and nuclear calcium waves of heart cells via activation of AT1 and AT2 receptors.

The aim of this work is to verify if Angiotensin II (Ang II) affects the frequency of spontaneous cytosolic and nuclear Ca2+ waves in chick embryonic cardiomyocytes and if this effect is mediated via the activation of AT1 and/or AT2 receptors. Using the rapid scan technique of confocal microscopy, we observed that Ang II (10(-8)M) increases the frequency of cytosolic and nuclear Ca2+ waves. This effect was accompanied by a decrease in the amplitude of nuclear Ca2+ waves and an absence of effect on the amplitude of cytosolic Ca2+ waves. The effect of the octapeptide on both frequency and amplitude of the nuclear waves was prevented by the AT1 receptor antagonist L158809. However, blockade of the AT2 receptor using the antagonist PD123319 (10(-7)M) only prevented the effect of Ang II on the frequency of Ca2+ waves. Furthermore, the effect was prevented by both a PKC inhibitor (bisindolylmaleimide) and a PKC activator (phorbol 12,13-dibutyrate). In addition, the Ang II effect was not prevented by the blocker of the pacemaker current If. These results demonstrate that Ang II, via the activation of its receptors AT1 and AT2, affects the frequency of spontaneous Ca2+ waves and this effect seems to be mediated by the PKC pathway.

Angiotensin II↗

PubMedDate not supplied

Immunofluorescence revealed the presence of NHE-1 in the nuclear membranes of rat cardiomyocytes and isolated nuclei of human, rabbit, and rat aortic and liver tissues.

Using immunofluorescence and 3-dimensional confocal microscopy techniques, the present study was designed to verify if NHE-1 is present at the level of the nuclear membrane in cells that are known to express this type of exchanger. Nuclei were isolated from aortic tissues of adult human, rabbit, and rats, as well as from liver tissues of human fetus, and adult rabbit and rat. In addition, cultured ventricular cardiomyocytes were isolated from 2-week-old rat. Our results showed the presence of NHE-1 in isolated nuclei of aortic vascular smooth muscle and liver of human, rabbit, and rat. NHE-1 seems to be distributed throughout the isolated nucleus and more particularly at the level of the nuclear membranes. The relative fluorescence density of NHE-1 was significantly higher (p < 0.05) in isolated liver nuclei of human, when compared with those of rabbit and rat. However, in isolated nuclei of aortic vascular smooth muscle, the relative fluorescence density of NHE-1 was significantly (p < 0.001) higher in the rabbit when compared with human and rat. In cultured rat ventricular cardiomyocytes, NHE-1 fluorescent labeling could be easily seen throughout the cell, including the nucleus, and more particularly at both the sarcolemma and the nuclear membranes. In rat cardiomyocytes, the relative fluorescence density of NHE-1 of the sarcolemma membrane, including the cytosol, was significantly lower than that of the whole nucleus (including the nuclear envelope membranes). In conclusion, our results showed that NHE-1 is present at the nuclear membranes and in the nucleoplasm and its distribution and density may depend on cell type and species used. These results suggest that nuclear membranes' NHE-1 may play a role in the modulation of intranuclear pH.

Adult↗