Cyclosporin A (CsA) is a potent immunosuppressive agent that has significantly improved graft survival in organ- and bone-marrow-transplant recipients. However, in the context of graft transplantation, CsA has been suggested to potentiate vascular disease by stimulating smooth-muscle cell (SMC) proliferation. As previous studies on the effect of CsA on smooth-muscle proliferation have afforded conflicting results, we conducted an in vitro study of the effect of two concentrations of CsA--10(-6) M (corresponding to the maximal concentration in patients) and 10(-7) M (corresponding to trough concentrations)--on cultured rat SMC proliferation, as assessed by [3H]thymidine incorporation into DNA and measuring cell number by a colorimetric method based on the quantitative staining of cell nuclei. In the presence of 0.5% fetal calf serum (FCS), 10(-6) M CsA induced an increase in [3H]thymidine incorporation into DNA (from 614.44 +/- 67.76 to 1,472.6 +/- 177.63 cpm/well; p < 0.05) with no increase in the number of cells. A cytotoxic effect for this dose was ruled out owing to the absence of significant levels of lactate dehydrogenase (LDH) activity in the supernatant. CsA, 10(-7) M, induced an increase in both [3H]thymidine incorporation into DNA (from 614.44 +/- 67.76 to 1,220.91 +/- 145.59 cpm/well) and cell number (82.49 +/- 6.16 to 165.79 +/- 10.48 cells x 10[3]; p < 0.05). In the presence of 10% FCS, the highest CsA concentration increased [3H]thymidine incorporation to 2,115.91 +/- 224.06 cpm/well, with no significant changes in cell number. However, the lowest CsA concentration increased both [3H]thymidine incorporation (to 3.752.58 +/- 525.06 cpm/well) and cell number (to 181.27 +/- 14.2 cells x 10[3]). These findings suggest that the proliferative effect of CsA on SMCs is variable and that it depends on the concentration of the drug, in support of the discordant results reported previously.

The aim of the present study was to investigate the role of renal nerves and atrial natriuretic factor (ANF) in the mechanisms responsible for the diuresis and antinatriuresis induced by morphine in rats in a normal state of hydration. Male Wistar rats weighing 350-400 g were divided into two groups: one group was subjected to bilateral renal denervation, whereas the other consisted of sham-operated controls. The animals were placed in individual metabolic cages, and morphine (1.25, 2.5, 5.0 or 10.0 mg/kg body weight) or vehicle (0.5 ml isotonic saline) was injected intraperitoneally. Urine was collected hourly for 1 h before and 3 h after morphine injection. The lower doses of morphine (1.25 and 2.5 mg/kg body weight) induced a transient increase in urine output (from 1.17 ± 0.12 to 2.49 ± 0.34 and from 0.78 ± 0.08 to 1.71 ± 0.18 µl/min, respectively). The diuretic response to these doses was similar in bilaterally denervated rats. Higher doses (5.0 and 10.0 mg/kg body weight) induced a marked but transient reduction in the urinary flow rate during the first hour (from 0.90+0.11 to 0.48+0.05 and from 1.37+0.17 to 0.45 ± 0.08 µl/min, respectively), followed by a delayed diuretic effect. The antidiuretic action of morphine was not observed in bilaterally denervated rats. In control rats, morphine induced a dose-dependent decrease in sodium excretion 1 h after administration, an effect that was blunted in the denervated group. The lower morphine doses (1.25 and 2.5 mg/kg body weight) elicited a transient increase in the glomerular filtration rate (GFR) in both control (from 1.23+0.12 to 1.67+0.17 and from 1.28+0.14 to 2.41+0.18 ml/min) and bilaterally denervated rats (from 1.29+0.14 to 1.66+0.17 and from 1.18+0.22 to 1.72+0.19 ml/min), whereas the higher doses (5.0 and 10.0 mg/kg body weight) produced a marked, transient GFR decrease in the controls (from 1.25+0.11 to 0.43 ± 0.05 and from 1.13+0.17 to 0.47 ± 0.08 ml/min) and bilaterally denervated animals (from 1.48+0.16 to 0.74 ± 0.09 and from 1.22+0.15 to 0.73 ± 0.06ml/ min), although the reduction was less pronounced with renal denervation. Morphine induced a transient, dose-dependent reduction in blood pressure (from 114+1 to 71 ± 6mm Hg at 10.0 mg/ kg body weight) and a dose-dependent elevation of plasma ANF. No differences in plasma ANF were observed between control and denervated animals under basal conditions (60 ± 7 vs. 42 ± 6 pg/ml) or after injection of 2.5 or 5.0 mg/kg of morphine (155+11 vs. 167 ± 9 and 360 ± 9 vs. 401+9 pg/ml, respectively). Our data suggest that the renal responses to intraperitoneal morphine administration derive from the integration of several different actions: (1) increased ANF release; (2) decreased arterial pressure; (3) subsequent activation of renal sympathetic activity, and (4) the direct effect of morphine on tubular function.

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Part I Introduction 1 Chapter 1.1 General introduction to the topic 1 1.2 Survey of the literature and scope of the present study 3 1.3 References Partii Measurement of ANP concentrations Chapter 2.1 Extraction method 2.2 Direct method 2.3 Validation of the antibody 2.4 Immunoreactivity of ANP in human plasma 2.5 Determination of cGMP concentrations 2.6 References Part III Influence of various physiological and sampling conditions on ANP concentrations Chapter 3.1 Blood sampling and handling of plasma samples 3.2 Venepuncture stress and menstrual cycle 3.3 Diurnal rhythm 3.4 Intra-individual variation 3.5 Posture and ANP 3.6 Exercise and ANP 101 3.7 References 107 Part IV Age-dependency of ANP Chapter 4.1 Age and immunoreactive ANP concentrations 4.2 Clearance of ANP 4.3 Dehydration and ANP 4.4 Volume loading and ANP 4.5 Infusion of ANP-Haemodynamic effects-Endocrine effects 4.6 References Part V Studies of ANP in pathophysiological states Chapter 5.1 Reciprocal changes in ANP and PRA during 171 treatment of pulmonary embolism 5.2 ANP after myocardial infarction 5.3 References 185