A study on the effects of some drugs on DOCA induced hypertension in the rat

Summary Chronic treatment with various drugs reduced the increase in arterial blood pressure, the ventricular hypertrophy and the thickening of pulmonary arterial and arteriolar walls.This work was supported by the Italian CNR (contract No. 7901928.04 and 7902391.65).     

Branchial vascularization in the eel: action of acetylcholine and adrenaline on the distribution of polymerizable resin in the different vascular compartments]

The current findings from gill vascular cast preparations in the eel emphasize the division in each primary lamella of the afferent vasculature into two efferent pathways: an arterial pathway (via the secondary lamellae and the efferent branchial artery to the dorsal aorta), a venous pathway (via the central lamellar compartment and the branchial vein to the sinus venosus). By the same technique two antagonist mechanisms have been shown presumably controlling the blood flow in both pathways. 1. Acetylcholine increases the filling of the central lamellar compartment by constricting the efferent arterial sphincters and therefore increases the venous return. 2. Epinephrine impairs the filling of the central lamellar compartment (by acting on alpha receptors) and dilates the arterial pathway (by acting on beta receptors). Therefore the stimulation of these two synergic receptors by epinephrine increases the systemic blood flow.     

Effect of sudden reductions of the arterial blood pressure on the mean diastolic coronary resistance

Summary At the beginning of a 10 sec arterial haemorrhage, vascular elasticity induces an increase of mean diastolic coronary resistance. Then, the increase is counteracted by the relaxation of the vascular musculature, which causes a coronary hyperaemia when, after the haemorrhage is arrested, the vascular wall is stretched by a sudden though slight increase of blood pressure.Acknowledgment. The authors wish to thank Mr Rodolfo Dalla Valle for his technical assistance.     

Altered hyperemic response of the coronary arterial bed in alloxan-diabetes

Reactive hyperemic responses of the coronary arterial bed, provoked by asphyxia or clamping of the coronary artery, were compared in alloxan-diabetic and metabolically healthy dogs. In alloxan-diabetic dogs the response of the coronary arterial bed lasted longer, and its reactivity to hypoxia was lower. Treatment with adenosine caused less vasodilation in diabetic animals than in controls. These changes may be due to the altered reactivity of diabetic vascular smooth muscle.     

Altered hyperemic response of the coronary arterial bed in alloxan-diabetes

Summary Reactive hyperemic responses of the coronary arterial bed, provoked by asphyxia or clamping of the coronary artery, were compared in alloxan-diabetic and metabolically healthy dogs. In alloxan-diabetic dogs the response of the coronary arterial bed lasted longer, and its reactivity to hypoxia was lower. Treatment with adenosine caused less vasodilation in diabetic animals than in controls. These changes may be due to the altered reactivity of diabetic vascular smooth muscle.     

Spontaneous morphine withdrawal from the rat spinal cord

A characteristic and reproducible sign of narcotic withdrawal is the naloxone induced increase in arterial pressure. In morphine-dependent rats allowed to undergo spontaneous withdrawal (6-24 h) and then transected at the spinal C-1 level, arterial pressure was maintained at a significantly higher level than either spinal-transected nondependent controls or morphine-dependent, spinal-transected rats pithed from C-1 to L-4. These findings indicate that the morphine-dependent spinal cord, independent of supraspinal influences, is able to exhibit an autonomic component of spontaneous withdrawal.     

Areas in the amygdala necessary to the operation of the vagosympathetic pressor reflex.

Lesions of portions of the basal and cortical amygdaloid nuclei and the stria terminalis reversed or abolished arterial pressor responses to ipsilateral centripetal vagal stimulation (CVS). Destruction of these particular limbic structures in the rat did not affect cardiopulmonary responses to CVS.     

Areas in the amygdala necessary to the operation of the vagosympathetic pressor reflex

Summary Lesions of portions of the basal and cortical amygdaloid nuclei and the stria terminalis reversed or abolished arterial pressor responses to ipsilateral centripetal vagal stimulation (CVS). Destruction of these particular limbic structures in the rat did not affect cardiopulmonary responses to CVS.     

Effect of angiotensin II on neonatal lamb carotid arteries.

Isometric tension was measured in arterial strips from neonatal lambs and adult sheep, after stimulation by angiotensin II. During the early maturation period immediately following birth (3 weeks) there was a progressive increase in sensitivity to the agent.     

Spontaneous morphine withdrawal from the rat spinal cord

Summary A characteristic and reproducible sign of narcotic withdrawal is the naloxone induced increase in arterial pressure. In morphine-dependent rats allowed to undergo spontaneous withdrawal (6–24 h) and then transected at the spinal C-1 level, arterial pressure was maintained at a significantly higher level than either spinal-transected nondependent controls or morphine-dependent, spinal-transected rats pithed from C-1 to L-4. These findings indicate that the morphine-dependent spinal cord, independent of supraspinal influences, is able to exhibit an autonomic component of spontaneous withdrawal.This study was supported by the Medical Research Service of the Veterans Administration. A preliminary report of aspects of this work appeared in Soc. Neurosci. Abs.10 (1984) 1113.     

Guanylate cyclase stimulation by nitro-compounds is dependent on free Ca2+

The stimulatory effect of nitro-compounds on arterial and hepatic guanylate cyclase became significantly depressed at 0.2 microM and higher concentrations of free Ca2+. The basal enzyme activity proved to be Ca2+-independent.     

Changes in the distensibility of the cat aortic arch induced by noradrenaline

Summary In the isolated preparation of the aortic arch of the cat, noradrenaline (NA) reduced at low pre-loads, and increased at high pre-loads, the arterial wall distensibility. For each dose of NA, the changes were directly related to the pressure level in the system.     

Flow-induced release of adenosine 5'-triphosphate from endothelial cells of the rat mesenteric arterial bed.

Adenosine 5'-triphosphate (ATP) was released into the perfusate of rat isolated mesenteric arterial beds during each of two consecutive increases in flow. There was no significant difference between the amounts of ATP released on each occasion. Substance P was also released into the perfusate by increased flow, although its release was more variable. Removal of the endothelium of the mesenteric vessels with sodium deoxycholate led to a significant reduction (74%) in the amount of ATP released compared with the release before the endothelium had been removed. This suggests that the ATP released into the mesenteric arterial perfusate during increased flow arises from endothelial cells.     

Altered adrenergic responses of the coronary arterial bed in alloxan-diabetic dogs

Summary The conductivity of the coronary arterial bed increased in healthy and decreased in alloxan-diabetic dogs in response to intracoronary administration of norepinephrine or sympathetic stimulation. This suggests a modification of adrenergic receptors sensitivity in diabetes.     

Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.     

Leukocyte mobilization from the guinea pig spleen by muscarinic cholinergic stimulation

Important interactions between the immune system and the nervous and endocrine systems have become increasingly accepted. The present results demonstrate that the cholinergic agonist carbacholine greatly increased the number of granulocytes and lymphocytes in the splenic venous blood, but not arterial blood, shortly after administration to guinea pigs. The effect was largely blocked by pretreatment with atropine. In contrast, animals treated with indomethacin had a decreased number of leukocytes in both splenic venous and arterial blood. A decrease in relative splenic weight due to carbacholine treatment was also blocked by atropine. However, cholinergic leukocyte mobilization, or that previously observed after adrenergic stimulation, may not be caused by capsule contraction since it is not accompanied by mobilization of erythrocytes. Furthermore, indomethacin, which potentiates the response of splenic smooth muscle to adrenergic stimuli, blocked the effect of noradrenaline (NA) on leukocyte mobilization.     

Antihypertensive and other cardiovascular effects of 2-(3-pyridyl)- and 2-(4-pyridyl)-4-trifluoromethylimidazoles.

2 new 4-trifluoromethylimidazole derivatives were found which lowered mean arterial pressure in renal and spontaneously hypertensive (SH) rats by the oral route. In SH rats, compounds A and B were 0.1 and 0.3 times, respectively, as potent as hydralazine. No tolerance development was observed in SH rats with either compound over a 1-week period. In anesthetized dogs, both compounds lowered arterial pressure and peripheral vascular resistance but increased cardiac output. By intraarterial administration, both compounds increased femoral arterial blood flow. These findings represent discovery of a new class of vasodilator durgs.     

Thermogenic response as the function of extravascular influx of infused noradrenaline

Summary The dynamic and static phases of the thermogenic response to i.v. infused noradrenaline (NA) do not reflect the arterial concentration of NA; according to the equation presented here they are a function of the influx rate.     

Antihypertensive and other cardiovascular effects of 2-(3-pyridyl)- and 2-(4-pyridyl)-4-trifluoromethylimidazoles

Summary 2 new 4-trifluoromethylimidazole derivatives were found which lowered mean arterial pressure in renal and spontaneously hypertensive (SH) rats by the oral route. In SH rats, compounds A and B were 0.1 and 0.3 times, respectively, as potent as hydralazine. No tolerance development was observed in SH rats with either compound over a 1-week period. In anesthetized dogs, both compounds lowered arterial pressure and peripheral vascular resistance but increased cardiac output. By intraarterial administration, both compounds increased femoral arterial blood flow. These findings represent discovery of a new class of vasodilator drugs.Deceased, May 31, 1978.     

Effect of angiotensin II on neonatal lamb carotid arteries

Summary Isometric tension was measured in arterial strips from neonatal lambs and adult sheep, after stimulation by angiotensin II. During the early maturation period immediately following birth (3 weeks) there was a progressive increase in sensitivity to the agent.This study was supported by the Golden Empire Chapter of the American Heart Association and the United States Public Health Service, grant No. PHS HL 14780-03.