General pharmacological properties of the human corticotropin-releasing hormone corticorelin (human)

General pharmacological effects of the human corticotropin-releasing hormone, corticorelin (human) (CAS 86784-80-7), on the central nervous system, somatic nervous system, autonomic nervous system and smooth muscle, respiratory and circulatory system, digestive system and miscellaneous organs were investigated. 1. The central nervous system: Corticorelin (human) had little effect on hexobarbital-induced sleeping-time, maximal electroshock-induced convulsion, acetic acid-induced writhing, rota-rod performance. Corticorelin (human) at doses of more than 10 micrograms/kg i.v. induced flush of skin and pilo-erection, at doses of more than 30 micrograms/kg i.v. decreased body temperature, delayed expression of perphenazine-induced catalepsy and indicated hunched posture, and at the dose of 100 micrograms/kg i.v. induced the rise of awake-level and decrease of the total power of EEG, and decreased the spontaneous motor activity. 2. The somatic nervous system: Corticorelin (human) did not cause muscle relaxation in mice and had little effect on neuromuscular transmission in rats. No local anesthetic activity of corticorelin (human) was exhibited through inhibition of the corneal reflex in guinea pigs. 3. The autonomic nervous system and smooth muscle: Corticorelin (human) had no effect on the contraction of isolated ileum of guinea pigs induced by histamine and acetylcholine, and on the contraction of isolated trachea of guinea pigs induced by histamine, and the pupil diameter of rabbits. Corticorelin (human) at doses more than 30 micrograms/kg i.v. decreased spontaneous motility and contractile force of uterus of non-pregnant rabbits. 4. The respiratory and circulatory system: Corticorelin (human) had no effect on the contraction of isolated aorta of rats induced by norepinephrine. Corticorelin (human) at doses of more than 3 micrograms/kg i.v. decreased the blood pressure, increased heart rates and slightly increased the number of respiration in dogs. However, corticorelin (human) had no effect on ECG and femoral blood flow in dogs. 5. The digestive system: Corticorelin (human) at doses of more than 0.3 microgram/kg i.v. increased duodenal motility and contractile force, at doses of more than 1 microgram/kg i.v. increased colonic contractile force transiently and increased antral motility. Corticorelin (human) at doses of more than 3 micrograms/kg i.v. caused diarrhea and at doses of more than 30 micrograms/kg i.v. inhibited small intestinal propulsion in mice. Corticorelin (human) at dose of 100 micrograms/kg i.v. showed an inhibition of the gastric juice secretion and decreased the excretion of Na+, Cl- and H+ in rats. Corticorelin (human) produced slight gastric damages only at the highest dose of 100 micrograms/kg i.v.(ABSTRACT TRUNCATED AT 400 WORDS)

Suppression of rat deoxycorticosterone-salt hypertension by kallikrein-kinin system

Brown Norway kininogen-deficient rats had very low levels of plasma kininogens and lower levels of plasma prekallikrein, compared with those of normal rats of the same strain. Systolic blood pressure, determined by the tail-cuff method, of 5-week-old kininogen-deficient rats (106 +/- 0.4 mm Hg, n = 7) and the rate of systolic blood pressure increase with age were not different from those in normal rats. Weekly injections of deoxycorticosterone acetate (5 mg/kg s.c.) with 1% sodium chloride solution in drinking water after uninephrectomy at 7 weeks of age caused a gradual increase in the blood pressure of normal rats, reaching a plateau at 18 weeks of age, whereas that of deficient rats rose rapidly to 158 +/- 6 mm Hg 2 weeks after the start of treatment and continued to increase slightly, becoming significantly higher than normal rats at 8, 9, 10, 11, and 12 weeks of age (p less than 0.05 or 0.01). The levels of urinary prokallikrein and active kallikrein were slightly higher in deficient rats before deoxycorticosterone acetate-salt treatment but were not significantly increased after this treatment, whereas these levels in normal rats were increased 3.6- and 4.7-fold by this treatment. Urinary free kinin, collected from the ureter in untreated deficient rats, was below the detection limit. The plasma level of low molecular weight kininogen, the substrate of glandular kallikrein, was decreased in normal rats during the treatment. Continuous subcutaneous injection of aprotinin by an osmotic pump to normal rats induced significant increase in blood pressure. These results indicate that glandular kallikrein may play a suppressive role in deoxycorticosterone acetate-salt hypertension.

[Effects of intravenous and intracerebroventricular terazosin, prazosin and clonidine on spontaneous sympathetic outflow in rats]

The hypotensive activity of terazosin has been attributed to inhibition of postsynaptic alpha-1 adrenoceptors. The present study examined the influence of terazosin on spontaneous sympathetic outflow in anesthetize and immobilized rats. The effects on blood pressure and heart rate were also evaluated. Intravenously (i.v.) injected terazosin 0.3 mg/kg and prazosin 0.1 mg/kg increased a sympathetic outflow by 15.4 and 21.6%, respectively. These drugs produced a significant and long-lasting fall in blood pressure with slight heart rate change. On the contrary, clonidine 0.1 mg/kg, i.v. significantly inhibited the sympathetic outflow by 69.2%. The intracerebroventricularly administered 10 micrograms/kg clonidine also showed the sympathoinhibitory effect. However 3 micrograms/kg, i.c.v. of terazosin and prazosin increased the sympathetic tone by 16 and 7.2%. During these periods, in both drugs slightly decreased the blood pressure. These changes in hemodynamic parameters and nerve activities were obtained at 2 approximately 3 min after the i.c.v. administration. The 10 micrograms/kg, i.c.v. of terazosin and prazosin significantly inhibited the pressor response by phenylephrine 1 micrograms/kg, i.v. These results indicate the peripheral effect of terazosin and prazosin through the penetration of the drugs from the brain. The results provide evidence that terazosin, like prazosin, dose not affect cardiovascular regulation by a central action.

[Alpha-adrenoceptor blocking action of terazosin]

alpha-Adrenoceptor blocking activities and vascular relaxation activities of terazosin, a new antihypertensive agent, were studied. Terazosin had no effect on Ba2+, serotonin, angiotensin II and Ca2+ induced contractions in the isolated rat aorta. Terazosin competitively inhibited norepinephrine (NE) and phenylephrine (PE) induced contractions of the isolated rat aorta, and their pA2 values were 9.28 and 8.74, respectively. The potency of terazosin in the NE induced contraction was about 0.11, 8 and 176 times more than prazosin, phentolamine and yohimbine, respectively. The potency of terazosin in the PE induced contraction was about 0.09, 6 and 60 times more than prazosin, phentolamine and yohimbine. Terazosin (i.v.) competitively inhibited the PE induced pressor response. The "pA2" values of postsynaptic alpha-adrenoceptor blocking activity was 5.22, and its potency was about 0.05, 5 and 62.5 times more than prazosin, phentolamine and yohimbine, respectively. Terazosin (0.3 mg/kg, i.v. or less) did not show any significant effect on clonidine induced bradycardia during electrical stimulation of cardiac sympathetic nerve, whereas prazosin (0.3 mg/kg), phentolamine (0.1 mg/kg) and yohimbine (0.1 mg/kg) antagonized the effect of clonidine by 37%, 80.6% and 63.3%, respectively. Terazosin, 0.3 and 1 mg/kg, p.o., antagonized the PE (3 micrograms/kg, i.v.) induced pressor response in conscious unrestrained rats. This effect lasted for 8 hr in the case of 0.3 mg/kg and lasted for 12 hr in the case of 1 mg/kg. Thus, it is strong suggested that the antihypertensive effect of terazosin is based on the postsynaptic alpha-adrenoceptor blocking action.

Pyrimidine derivatives. 4. Synthesis and antihypertensive activity of 4-amino-2-(4-cinnamoylpiperazino)-6,7-dimethoxyquinazoline derivatives

A series of 30 4-amino-2-(4-cinnamoylpiperazino)-6,7-dimethoxyquinazoline derivatives was prepared and tested for their ability to reduce blood pressure in conscious, spontaneously hypertensive rates (SHR). A number of these compounds, notably 4-amino-2-(4-cinnamoylpiperazino)-6,7-dimethoxyquinazolines 3a (R1 = H; R2 = Ph), 3j (R1 = H; R2 = 4-EtOPh), and 5a (R1 = H; R2 = 2-furyl), showed activity at oral doses of 0.3-10 mg/kg. The effects of the 4-substituents of the piperazino group on activity are discussed. Compounds 3a, 3j, and 5a were effective in renal hypertensive rats at oral doses of 3 and 10 mg/kg and showed alpha-adrenoceptor blocking effects in isolated aortas of rats. A 5-day consecutive oral administration of 3a and 3j in SHR did not lead to development of tolerance.