Neurogenic constrictor response of isolated small renal arteries in rats after 2-week simulated microgravity.

The study was aimed at investigation of the effects of 2-week tail suspension upon the constrictor responses of isolated small renal arteries in rats. 1st-2nd-order branches of renal artery were perfused with saline under the constant flow conditions. Constrictor responses to electrical stimulation of periarterial nerves, noradrenaline and serotonin were investigated.

Effect of two-week tail suspension on forelimb and hindlimb [correction of hindlimd] small arteries in rats.

This study was aimed at comparing the effect of 2-week tail suspension on the characteristics of median artery and saphenous artery isolated from forelimb and hindlimb, accordingly. The segments of arteries were mounted in two-channel myograph for recording their isometric wall tension. In post-suspension rats segments of saphenous artery showed augmented sensitivity to noradrenaline and serotonin.

Rho kinase inhibition partly weakens myogenic reactivity in rat small arteries by changing calcium sensitivity.

The hypothesis that Rho kinase is involved in myogenic reactivity was investigated in pressurized rat tail small arteries using videomicroscopic diameter determination and calcium fluorimetry. The potent Rho kinase inhibitor Y-27632 reversibly increased vessel diameter at 80 mmHg without changing the intracellular calcium concentration ([Ca](i)) shifting the relationship between diameter change and [Ca](i) to higher calcium levels. Neither endothelium removal nor inhibition of neural transmission affected the Y-27632-induced effect.

Urocortin relaxes rat tail arteries by a PKA-mediated reduction of the sensitivity of the contractile apparatus for calcium.

1. Urocortin is an endogenous vasodilator although the mechanism of vasorelaxation is not completely understood. The hypothesis that an alteration of smooth muscle calcium concentration is involved was tested using isometric tension recording and calcium fluorimetry.

Stimulatory effect of opioid peptides and naloxone on rat spinal cord cells in primary dissociated culture.

Opioid peptides leu-enkephalin, a synthetic analog of enkephalin dalargin and an opiate receptor blocker naloxone were studied for their morphological effect on the cells of dissociated cultures of rat spinal cord. Low density seeding of cells (3.10(5);6.

Beta-blocker action on lymphocyte proliferative response in essential hypertension.

The proliferative response of phytohaemagglutinin (PHA) - stimulated lymphocytes of healthy donors and hypertensive subjects was analysed according to 3H-thymidine incorporation and cell cycle phase position on a flow cytofluorimeter. 3H-thymidine uptake and the percentage of cells in (S + G2) phase were significantly lower in hypertensive patients. After short-term propranolol administration the lymphocyte blastogenic response in essential hypertension increased by 30--100%.

Stimulatory effect of substance P on sympathetic ganglia and spinal cord in culture.

Studies with organotypic culture of sympathetic ganglia and spinal cord revealed that substance P at concentrations of 10(-5) to 10(-12) M and 10(-5) to 10(-14) M exerts a marked growth-stimulating effect on sympathetic ganglia and spinal cord, respectively. In the presence of substance P, the intensity of sympathetic ganglion growth exceeds control values 3.0-4.

Effects of opioid peptides and naloxone on nervous tissue in culture.

It was shown that opioid peptides stimulate nervous tissue growth in culture in the rat, which manifests itself in augmented outgrowth of neurites from explants and in an increase in the number of glial and fibroblast-like cells in the growth zone. The effects of opioid peptides ([Leu]- and [Met]-enkephalins, beta- and gamma-endorphins and some synthetic analogues of [Leu]-enkephalin) on the growth of organotypic cultures of rat sympathetic and dorsal root ganglia and spinal cord were investigated. Neurite outgrowth, cell composition, and size of the growth zone as well as the dynamics of its formation were estimated.