Subject(s)
Neoplasms/therapy , Animals , Combined Modality Therapy , Humans , Neoplasms/physiopathology , Signal Transduction , VasoconstrictionSubject(s)
Antineoplastic Agents/administration & dosage , Genital Neoplasms, Female/drug therapy , Genital Neoplasms, Female/radiotherapy , Hyperthermia, Induced , Vasomotor System/radiation effects , Animals , Bleomycin/administration & dosage , Combined Modality Therapy , Doxorubicin/administration & dosage , Female , Genital Neoplasms, Female/blood supply , Humans , Rats , Vasoconstriction/drug effects , Vasoconstriction/radiation effects , Vasomotor System/drug effectsABSTRACT
The reaction of isolated helical strips of rat aorta to X-irradiation was studied: X-rays (50 kV) induced a reproducible, reversible contractile response at threshold doses of 2.5 Gy (60 Gy/min) and 10 Gy (30 Gy/min). After repeated irradiation with the same doses at equal time intervals and constant dose-rate (for example 50 Gy every 15 min, dose-rate 60 Gy/min) the contractile response was progressively diminished, i.e. a tachyphylaxis appeared. The preparations still reacted even after total doses over 1000 Gy. The X-ray induced contractile responses were dose- and dose-rate dependent. Quantitative analysis indicated no essential differences in the radiation-induced contractile response when recorded under isometric or isotonic conditions. After hypothermia (20 degrees C) or hyperthermia (42 degrees C) no visible radiation response could be induced. Part of the aortic strips were spontaneously active: X-ray doses of 5 to 10 Gy stimulated, while doses of 100 to 200 Gy inhibited or blocked the spontaneous phasic activity. A comparison between the immediate X-ray reaction of vascular and non-vascular smooth muscle preparations is given. Participation of cholinergic and adrenergic mechanisms in the X-ray induced contractions of rat aorta seems to be ruled out, because the blocking agents atropine, phentolamine, and bretylium had no effect.
Subject(s)
Muscle Contraction/radiation effects , Muscle, Smooth, Vascular/radiation effects , Animals , Aorta/radiation effects , Atropine/pharmacology , In Vitro Techniques , Isometric Contraction/radiation effects , Muscle Contraction/drug effects , Rats , Rats, Inbred Strains , Tachyphylaxis/radiation effects , TemperatureABSTRACT
The action of X-rays (50 kV, filtered by 0.3 mm Al) on helical strip of frog aorta (rana esculenta) has been investigated. The isolated preparations have a stable basal tone and are radio-sensitive to X-rays which induce reversible, dose-dependent, contractile responses. After repeated irradiation tachyphylaxis appears. The threshold doses are about 250 Rat 3 to 6 kR/min, antiadrenergic (phentolamine, propranolol), anticholinergic (atropin), antihistaminic (Neo-Bridal) and serotoninergic (Deseril) drugs have no visible influence on the X-ray induced reaction, i.e. these action mechanisms of the irradiation-induced contraction do not seem probable. Theophylline and cAMP inhibit the X-ray contraction probably non-specifically. Indometacin also inhibits the X-ray contraction: this suggests participation of prostaglandin-mechanism on the contraction of frog aorta after irradiation.
Subject(s)
Aorta/radiation effects , Muscle Contraction/radiation effects , Animals , Atropine/pharmacology , Cyclic AMP/pharmacology , Indomethacin/pharmacology , Methysergide/pharmacology , Muscle Contraction/drug effects , Muscle, Smooth/radiation effects , Phentolamine/pharmacology , Propranolol/pharmacology , Radiation Dosage , Rana esculenta , Theophylline/pharmacologyABSTRACT
The vasodilator and tocolytic substance buphenin (10 mumol/l) stimulated the spontaneous phasic activity of some (8 out of 18) isolated rat portal vein preparations; 0,1-1 mmol/l buphenin diminished or abolished the activity in all preparations. The isotonic and isometric tonic contractions of portal vein in response to adrenaline, noradrenaline and phenylephrine (0,1-1 mumol/l) disappeared almost completely after addition of buphenin in equimolar concentrations, whereas acetylcholine contractions persisted. The beta-adrenergic blocking agents propranolol and dichloisoprenaline (10 mumol/l) only slightly antagonized the inhibitory effect of buphenin on the contractile responses to catecholamines. It is concluded that buphenin exerts dual action upon rat portal vein: the drug partially stimulates the beta-receptors and partially blocks the alpha-adrenergic receptors.
Subject(s)
Muscle, Smooth, Vascular/drug effects , Nylidrin/pharmacology , Acetylcholine/pharmacology , Animals , Epinephrine/pharmacology , In Vitro Techniques , Male , Portal Vein/drug effects , Propranolol/pharmacology , Rats , Time FactorsABSTRACT
The mechanical activity (isotonic registration) of isolated detrusor (smooth) muscle preparations from the human urinary bladder (surgical material) is investigated. The preparations reacted on X-irradiation (50 kV) with an immediate dose-dependent tonic contraction at threshold-doses of 100 to 1000 R (1 to 3 kR/min). The contraction was either reversible, semireversible or persistent, and the basal muscle tone was elevated. A tachyphylactic reaction was observed. The phasic activity of the preparations was temporarily increased, then inhibited after irradiation. The radiation-induced changes of the human and guinea-pig detrusor muscle are compared and their possible relation to the functional disturbances of the urinary bladder after radiotherapy is discussed.
Subject(s)
Muscle, Smooth/radiation effects , Animals , Female , Guinea Pigs , Humans , Male , Muscle Contraction , Muscle Tonus/radiation effects , Radiation Dosage , Urinary Bladder/radiation effectsABSTRACT
2-Mercaptoethylguanidine (MEG) enhances the hypotension reaction to bradykinine and kallidine injections. In normal and spinal rats the secondary rise of the blood pressure after bradykinine, caused by catecholamine liberation, was transformed into a hypotension through MEG. These effects are partially interpreted as sympatholytic effects of MEG.
Subject(s)
Blood Pressure/drug effects , Bradykinin/pharmacology , Guanidines/pharmacology , Kallidin/pharmacology , Animals , Decerebrate State , Drug Interactions , Hypotension/chemically induced , Male , RatsABSTRACT
Tetrodotoxin (10- minus 8 to 10- minus 6 g/ml) blocked the contractile responses of isolated guinea-pig urinary bladder preparation to electrical (25 and 100 Hz) neural but not to transmural stimulation and to X-irradiation (50 kV, 20 kR/min, 20 kR). The irradiation had no influence on the bladder responses to electrical and hormonal (acetylcholine and histamine) stimulation. It is concluded that the X-ray-induced contraction is of myogenic origin and that it is possibly not related to the electro-mechanical coupling system.