Study on the mechanism of 5-HT-induced tachycardia in the pithed rat

1. Intravenous infusion of serotonin (5-HT) (2.5, 5, 10 and 20 micrograms/kg/min) in pithed rats induced a dose-dependent sustained tachycardia. 2. Pretreatment by phentolamine or diltiazem did not modify the chronotropic response to 5-HT. In contrast, atenolol antagonized this tachycardia and the 5-HT antagonists methysergide, ketanserin and MDL 72222 reduced it. 3. The 5-HT-induced tachycardia was abolished by desipramine and was not affected by fluvoxamine, a specific 5-HT uptake inhibitor. Surrenalectomy did not change the response to 5-HT but catecholamine depletion by reserpine markedly inhibited it. 4. Infusion of 5-HT increased the ratio of noradrenaline (NA) in the heart to NA in plasma, from 1.70 in control group to 2.76 in treated group (P less than 0.05). Desipramine inhibited this effect. 5. It was concluded that the tachycardia induced by an infusion of 5-HT in pithed rat results from a complex mechanism involving mainly the release of NA from the cardiac sympathetic nerves and a less important direct 5-HT2 mechanism.

Peripheral and central cardiovascular effects of ketanserin in conscious normotensive rats

The aim of the present study was to evaluate the effects of low doses of ketanserin, close to therapeutic ones, in conscious normotensive rats and to compare the different thresholds of 5-HT2- and alpha-antagonist properties and central sympatho-inhibitory activity. Male Sprague-Dawley rats (250-300 g) were used. Fourty-eight hr before experimentation, indwelling venous and arterial catheters were placed in each rat under light anaesthesia, and exteriorized through the interscapular skin. Drugs injected by i.v. route were ketanserin (50, 100, 200 micrograms/kg), serotonin (50 micrograms/kg), noradrenaline (1 microgram/kg), angiotensin (0.5 microgram/kg), nitroglycerin (200 micrograms/kg) and histamine (100 micrograms/kg). Ketanserin induced a short-lasting reduction in blood pressure and did not modify heart rate. At the dose of 50 micrograms/kg, this compound fully inhibited the pressor effect of serotonin, without modifying its hypotensive responses; after 200 micrograms/kg, ketanserin reduced by 50% the pressor effect of noradrenaline. Comparison of antagonistic activities on phenylephrine and noradrenaline pressor responses showed a selective blockade of alpha 1-adrenoceptors by 100 micrograms/kg ketanserin. In contrast, the angiotensin hypertensive response was unchanged. Reflex bradycardia after noradrenaline and angiotensin was reduced by 100 micrograms/kg ketanserin, whereas nitroglycerin and histamine effects were unaffected. In conclusion, administration of increasing low doses of ketanserin showed that blockade of 5-HT2-receptors appears in first, then a central sympatho-inhibitory effect and a selective alpha 1-adrenolytic activity occur. In addition, baroreceptor sensitivity seems not to be affected.

Disposition of unchanged cisplatin in patients with ovarian cancer

The disposition of cisplatin (cis-diamminedichloroplatinum II) was studied in the first course of treatment in seven patients (56 +/- 12 years) with ovarian carcinoma by analytic methodology specific for the unchanged drug. Particular attention was paid to rapid blood and urine sample processing to avoid drug losses. Patients were catheterized for urine collections. During and after infusion, plasma levels of unbound cisplatin were simultaneously fitted to a one-compartment model. Creatinine clearance was determined at the same time as cisplatin renal clearance and was 38 +/- 16 ml/min/m2. Total clearance of unbound cisplatin was 253 +/- 48 ml/min/m2 and volume of distribution was 11.5 +/- 2.7 L/m2. Cisplatin half-life was similar when determined from plasma (31.6 +/- 6.0 minutes) or urinary excretion rate data (24.4 +/- 4.0 minutes). Urinary excretion of unchanged drug was 23.3% +/- 8.6% of the dose and renal clearance 56.9 +/- 18.0 ml/min/m2. Renal clearance exceeded creatinine clearance in all patients ratio = 1.9 +/- 1.2), confirming previous suggestions of active renal tubular secretion of cisplatin. Renal clearance was nonlinear with time in two of the patients who received the 2-hour infusion, possibly reflecting changing renal tubular reabsorption. Pharmacokinetic studies of unchanged cisplatin rather than total platinum are therefore practical and could be pursued in further studies defining cisplatin disposition in patients.

Tissue distribution of acebutolol in mature normotensive and stroke-prone spontaneously hypertensive rats

Tissue distribution of acebutolol was studied in 33-week-old normotensive (WKY) and Okamoto stroke-prone (SHR-SP) rats, 30 min after an i.v. administration, by using 14C-acebutolol. Plasma level of acebutolol was higher in WKY than in SHR-SP. Aorta, kidney, liver and muscle radioactivity/plasma radioactivity ratios were higher in SHR-SP than in WKY. The brain/plasma radioactivity ratio was very low and similar in the two groups. The drug distribution was the same in the two groups except in medulla + corpus trapezoides where drug concentration was greater in SHR-SP. These results, compared with previous ones, show an age-related evolution in pathological state in SHR-SP. They point out a specific concentration of the beta-blocking drug in a defined part of the brain, namely medulla + corpus trapezoides.

Chronic subcutaneous treatment with acebutolol: haemodynamic effects and metabolism in spontaneously hypertensive rats

Chronic administration of acebutolol (15 mg kg-1 s.c. three times a week for five weeks, then 30 mg kg-1 for three weeks) did not lower blood pressure in 17 and 33 weeks-old spontaneously hypertensive rats (SHR). At the end of this treatment, the plasma concentrations of acebutolol and diacetolol were measured by HPLC. After 24 h, acebutolol was absent from plasma while diacetolol was lower after chronic treatment than after acute administration. Twenty-four hours after the last injection of acebutolol, both isoprenaline-induced tachycardia and vasodilatation were reduced. The vasomotor agents, noradrenaline, bradykinin and angiotensin, exhibited the same activity in control and treated SHR. These findings suggest that the lack of antihypertensive effect of acebutolol in SHR may be the result of a decrease in diacetolol formation together with blockade of beta 2 vascular receptors.

Central action of beta-adrenoceptor antagonists on blood pressure after acute administration in rats

The effect of an i.v. administration of some beta-adrenergic blocking drugs on blood pressure has been investigated in rats after blood-brain barrier (BBB) opening. Practolol and atenolol which do not penetrate the BBB, induced an immediate hypotensive effect after BBB breakdown by intracarotid (i.c.) injection of cetrimonium. In 39 week-old spontaneously hypertensive rats, practolol (15 mg/kg i.v.) and atenolol (3 mg/kg i.v.) induced a large drop in blood pressure while only a slight decrease was shown in normotensive ones. Likewise, acebutolol induced a significantly greater hypotension after BBB damage. On the other hand, the effects of dl-propranolol (5 mg/kg), quinidine (2.5 mg/kg) and isoproterenol (3 micrograms/kg) on blood pressure were not modified by pretreatment with cetrimonium i.c., while the hypotension induced by d-propranolol (5 mg/kg) was shortened. These results indicate that beta-adrenergic blocking agents with a low degree of lipophily can induce a hypotensive effect when their penetration into brain is largely enhanced after BBB opening either by prolonged hypertension or by cetrimonium. This effect is only dependent on their action on beta-adrenoreceptors; membrane stabilizing effect and intrinsic sympathomimetic activity do not seem to be involved.

A pharmacokinetic evaluation of IM administration of bleomycin oil suspension

Bleomycin oil suspension was given IM twice daily to four patients, and bleomycin saline solution infused to three patients with cervical carcinoma. The serum levels of bleomycin were followed for 12 h by radioimmunoassay. Both regimens revealed comparable side effects. Only minor responses were seen. Bleomycin oil suspension produced prolonged levels of bleomycin in serum.

Mitomycin C (MCC) in advanced soft tissue sarcoma: a phase II study of the EORTC Soft Tissue and Bone Sarcoma Group

Mitomycin C at a dose of 12 mg/m2 i.v. q 3 weeks was administered to 34 patients with measurable progressive advanced soft tissue sarcomas. No objective response was observed although in one of the 12 patients with overall stabilisation of disease a partial response was reported in lung lesions. The side-effects observed in this group of patients were generally mild. On the basis of this result the application of mitomycin C in this disease cannot be recommended.

Cardiovascular effects of drugs acting on the autonomous nervous system, in awake, normotensive and hypertensive rats

A study has been carried out in awake normotensive (WKY), spontaneously hypertensive (SHR) and renal hypertensive (RHR) rats in order to compare the reactivity of the autonomous nervous system using different indwelling catheterizations. In all cases, a jugular catheter was implanted for i.v. injections. The arterial cannula was implanted in the femoral artery (group 1) or in the right carotid artery (group 2), where the catheter was routed over 20 mm towards the heart, reaching the aortic arch. The plasma catecholamines levels were lower in the RHR than in the WKY or SHR, and whatever the strain, lower in group 2 than in group 1. In the WKY and the RHR, the mean blood pressure was higher in group 2 than in group 1. The tachycardia induced by isoprenaline and the pressor response to noradrenaline were higher in the SHR than in the WKY and in the RHR. By contrast, the reflex bradycardia was lower. Furthermore, the procedure of catheterization could modify the cardiovascular responses induced by adrenergic and cholinergic agents. These results demonstrate that indwelling catheterizations cannot be performed safely in the rat when studying effects on cardiac performance or vascular reactivity.

Acute haemodynamic effects and tissue distribution of acebutolol in normotensive and spontaneously hypertensive rats

Acute i.v. administration of 15 mg/kg acebutolol in normotensive (WKY), Okamoto (SHR) and Okamoto stroke-prone (SHR-SP) awake rats resulted in weak effects on blood pressure and in bradycardia more marked in SHR-SP. Thirty minutes after i.v. administration, lung and renal uptake of [14C]acebutolol was reduced in SHR compared to other rats. Muscle uptake was higher in SHR and blood concentration was higher in SHR-SP. Brain levels were low and similar in all rats. Plasma protein binding was identical in all rats. These results are discussed according to the characteristics of the three strains studied.

Prevalence of antibodies to herpes simplex virus and frequency of HLA antigens in patients with preinvasive and invasive cervical cancer

Previous herpes simplex virus type 2 (HSV-2) infections are known to predispose women for the development of cervical cancer, but causal relationship between the virus and the cancer has never been proven. Forty-six patients with cervical carcinoma (13 with preinvasive lesions and 33 with various stages of invasive disease) were selected for the present study. Among the patients 96% were seropositive for the presence of antibodies to herpes simplex virus compared to 87% of the 30 controls. Antibodies specific for HSV-2 were found in the sera from 24% of the patients and 17% of the controls by the use of an immunoblotting test. Patients and controls were typed for HLA-A,B,C and D/DR antigens, but no significant associations were found.

Whole-body distribution of radioactivity after intraperitoneal administration of 32P colloids

The whole-body distribution of radioactivity after intraperitoneal instillation of 32P-labelled chromic hydroxide particles has been studied in patients operated for early-stage ovarian cancer. Gamma-camera imaging of the abdominal 32P-distribution revealed that the administration procedure was critical for obtaining a homogeneous plating of the radiocolloids on the serosal surface. Dose calculations based on a uniform distribution of 32P in a capillary layer covering the intraperitoneal surface gave an estimated tissue surface dose of about 30 Gy per 370 MBq of 32P administered. The amount of 32P in peripheral blood increased for seven days after instillation followed by a continuous decrease. Bone marrow concentration was from two to five times as high as that in blood, but the total amounts were too small to give significant radiation doses. Gel chromatography showed that 33% of the activity in blood consisted of high molecular weight material, probably colloids. The remainder of the activity (67%) was attached to material of very low molecular weight, appearing as a consequence of physiological degradation of the colloids.

Mechanism of the hypotensive action of practolol in the anesthetized rat

Cardiovascular effects of acute administration of practolol were studied in groups of normotensive and spontaneously hypertensive rats. In some of these animals a strong and long-lasting hypotension was shown, resulting from a decrease in the total peripheral resistance. This hypotension was impaired by preventive propranolol administration, and did not result from a direct vascular effect. Moreover, it was previously reported that practolol induced a strong and long-lasting hypotension in all normotensive and hypertensive rats after blood-brain barrier disruption. From these experiments it is suggested that the blood pressure decrease observed in some groups of Okamoto rats may be due to a practolol action on central beta-receptors. The intensity of hypotension depends on the molecule penetration in the central nervous system, and seems to be related to blood-brain barrier lesions induced by genetic hypertension.

Acute cardiovascular activity of beta-adrenoceptor blocking drugs in awake or anaesthetized normotensive and hypertensive rats

The effects of intravenous dl-propranolol (5 mg/kg), 1- and d-alprenolol (5 mg/kg), on blood pressure, heart rate, cardiac output and total peripheral resistance were investigated in normotensive and spontaneously, renal or neurogenic hypertensive rats. The animals were either awake or anaesthetized with urethane, chloralose or pentobarbital. Anaesthesia may induce hemodynamic changes in hypertensive rats; thus urethane decreased peripheral vascular resistance in spontaneously hypertensive rats. In anaesthetized rats, dl-propranolol, 1- and d-alprenolol caused significant falls in blood pressure, heart rate and cardiac output. The hypotensive activity was related to the initial blood pressure. Peripheral vascular resistance remained unchanged except in spontaneously hypertensive, chloralose anaesthetized rats. 1-Alprenolol had less cardiac effects than dl-propranolol. The decrease of blood pressure was shorter and/or smaller after d-alprenolol than after 1-alprenolol. In normotensive and renal hypertensive awake rats, dl-propranolol induced a short fall of blood pressure, due to a decrease of heart rate and cardiac output. These effects, except bradycardia, were not observed in spontaneously hypertensive rats. These results suggest that differences in the initial vascular state, in the hypertensive models and in the anaesthetics used can explain the variability of the responses to beta-adrenergic blocking drugs. Moreover, beta-blocking as well as quinidine-like activities are involved in the cardiovascular responses to dl-propranolol, d-alprenolol and 1-alprenolol studied here.

Demonstration of an FSH receptor in a functioning granulosa cell tumour. The effect of gonadotrophin treatment on its viability following transplantation to nude mice

Hormone production in a patient suffering from a late recurrence of a granulosa cell tumour has been studied pre- and post-operatively, and a vein on the tumour surface was cannulated at operation to collect tumour vein blood for pre-operative studies. Elevation in the plasma oestradiol level and depression in FSH and LH were found pre-operatively, and elevations were found in tumour vein oestradiol and 17alpha-hydroxyprogsterone. Plasma oestradiol level returned to normal postoperatively whereas FSH and LH levels were persistently depressed. FSH receptors were found in this tumour, and on the basis of this finding, gonadotrophins were given to athymic nude mice in an attempt to support the growth of the granulosa cell tumour implanted in these animals. We demonstrated that gonadotrophins have supported the tumour tissue, but not promoted growth.

Simple hysterectomy in the presence of invasive cervical cancer

During the years 1956-69, 74 cases of invasive cervical carcinoma treated by simple hysterectomy were referred to the Norwegian Radium Hospital. The 5 year survival for those with free operative borders was 77.1% as compared with 30.7% for those cases in which the tumour was transected during operation. Before operation for a supposed benign condition, cancer should always be ruled out. If simple hysterectomy is performed and cervical cancer found in the specimen, immediate postoperative megavoltage radiotherapy affords the best chance of cure.

Heterologous growth of human ovarian cancer. A new in vivo testing system

Successful heterotransplantation of ovarian cancer in the mouse mutant, nude is described, with serial transmission, in one case to date. Light and electron microscopic examination of this tumour, a poorly differentiated adenocarcinoma, has not revealed any alteration in its morphology after six passages. Tumour-bearing mice have been treated with ThioTEPA or 5-Fluoro-Uracil, in an attempt to see if they show a similar effect to that seen in the patient. ThioTEPA resulted in a marked regression, whilst there was no effect from 5-Fluoro-Uracil, on tumour growth--confirming the ThioTEPA effect seen in the patient.

A pilot experiment to compare regression of transplants of two different human tumors in athymic nude mice following single exposures to 60co radiation

Human tumor transplants were grown in a thymus defective nude mouse mutant (nu/nu BALB/c/A/Bom). Procedures for local irradiation of the tumor with 60Co-radiation are described. An introductory test of the usefulness of these transplants in studies of radiation effects on human tumors is performed by investigation of the time course of regression of adenocarcinoma transplants in six mice following single exposures of 375, 750, 1180 and 1575 rd, respectively, and malignant melanoma transplants in two mice following single exposures to 1475 and 2420 rd, respectively. The higher radioresistance of the malignant melanomas relative to that of the ovarian tumor is expected on the basis of clinical experience and indicates that radiation effects on human tissue implants in nude mice mirror some of the fundamental features of the in situ situation.

A preliminary experiment on regression of human ovarian tumor transplants in athymic nude mice following a single exposure to 60Co radiation

Human ovarian tumour transplants (AN-LE) are grown in the thymus defective nude mouse mutant (nu/nu BALB/c/A/Bom). Procedures for local irradiation of the tumors with 60Co-radiation are described. An introductory test of the usefulness of these transplants in studies of radiation effects on human tumors is performed by investigation of the time course of regression of AN-LE transplants in 6 mice, following single exposures to 375, 750 1 180, and 1 575 rad, respectively.