Responses of monkey, rabbit and dog internal carotid arteries to atrial natriuretic factor

Effects of atrial natriuretic factor (ANF) on monkey, rabbit and dog internal carotid arteries were investigated. ANF caused a concentration-dependent relaxation in arterial strips submaximally precontracted with noradrenaline, 5-hydroxytryptamine, or high-potassium solution (10-30 mM). The response was greatest in the monkey arteries and least in the dog arteries. These results suggest that there is a marked species difference in the ANF-induced relaxation of the internal carotid arteries.     

Some species differences in cardiovascular responses to intravenously injected leucine-enkephalin

Studies were conducted to determine the cardiovascular responses to leucine-enkephalin (L-enk) in three different species of animals; rabbit, dog and monkey. All animals were anesthetized with pentobarbital sodium after sedation with ketamine. Mean blood pressure (MBP) and heart rate (HR) were simultaneously monitored. The pressor and HR responses to bilateral carotid occlusion (BCO) were determined before injection of L-enk. Increased MBP and HR due to BCO in monkey were significantly greater than in the other two animal groups. Following i.v. injection of L-enk (5-30 micrograms/kg), a significant fall in MBP occurred in all groups in a dose-dependent manner; however, the time course of changes in MBP in rabbits was significantly shorter than that in the other animal groups. Significant decreases in HR after the injection of L-enk occurred in rabbits and dogs, whereas increases in HR occurred in monkeys. These results show that some cardiovascular responses to L-enk may be species dependent. These different cardiovascular responses to L-enk may be at least partly related to species differences in baroreceptor reflex sensitivity.     

Elastase, collagenase and the radial elastic properties of arteries

Studies were performed on 203 pairs of dog carotid arteries subjected to unidirectional radial compression. Treatment with 80 U/ml purified elastase for 90 min decreased radial stress, but treatment with 640 U/ml collagenase for 90 min did not. These data suggest that elastin, but not collagen, contributes to wall resistance to radial compression.     

Elastase,collagenase and the radial elastic properties of arteries

Summary Studies were performed on 203 pairs of dog carotid arteries subjected to unidirectional radial compression. Treatment with 80 U/ml purified elastase for 90 min decreased radial stress, but treatment with 640 U/ml collagenase for 90 min did not. These data suggest that elastin, but not collagen, contributes to wall resistance to radial compression.     

Some species differences in cardiovascular responses to intravenously injected leucine-enkephalin

Summary Studies were conducted to determine the cardiovascular responses to leucine-enkephalin (L-enk) in three different species of animals; rabbit, dog and monkey. All animals were anesthetized with pentobarbital sodium after sedation with ketamine. Mean blood pressure (MBP) and heart rate (HR) were simultaneously monitored. The pressor and HR responses to bilateral carotid occlusion (BCO) were determined before injection of L-enk. Increased MBP and HR due to BCO in monkey were significantly greater than in the other two animal groups. Following i.v. injection of L-enk (5–30 g/kg), a significant fall in MBP occurred in all groups in a dose-dependent manner; however, the time course of changes in MBP in rabbits was significantly shorter than that in the other animal groups. Significant in HR after the injection of L-enk occurred in rabbits and dogs, whereas increases in HR occurred in monkeys. These results show that some cardiovascular responses to L-enk may be species dependent. These different cardiovascular responses to L-enk may be at least partly related to species differences in baroreceptor reflex sensitivity.     

Vitamin D receptors in heart: Effects on atrial natiuretic factor

We report that receptors for vitamin D exist in distinct regions of the heart in female and male mice, predominantly in the right atrium where most of the cardial atrial natriuretic peptide (ANF) is produced. Tritiated 1,25-dihydroxyvitamin D₃ (1,25-D₃, vitamin D, soltriol) and ANF are colocalized in nuclei and cytoplasm respectively in identical cardiomyocytes. Changes of ANF tissue and blood levels under dietary deficiency and treatment with 1,25-D₃ suggest direct genomic actions of vitamin D on myoendocrine cells of the atrium for the regulation of ANF manufacture and secretion. These results were obtained by combining thaw-mount autoradiography with immunocytochemistry using tritiated 1,25-D₃ and an antibody against rat ANF. This antibody was also used in a radioimmunoassay to determine atrial natriuretic factor in plasma, atria and ventricles of normal or vitamin D-deficient mice.     

Triphasic vascular effects of thiol compounds and their oxidized forms on dog coronary arteries

The vascular effects of 2-mercaptoethanol, cysteamine, L-cysteine, glutathione (GSH), cystamine and oxidized GSH (GSSG) on the isometric tension of isolated dog coronary arterial strips were examined, and these effects were compared with the triphasic response induced by dithiothreitol (DTT); a rapid and weak contraction (phase A), an intervening slow relaxation (phase B) and a slowly-developing strong contraction (phase C) which we previously reported. The responses of the arteries induced by 2-mercaptoethanol, cysteamine and L-cysteine consisted of phases A, B and C. The order of contractile potency (ED₅₀ of phase C) was DTTL-cysteine>2-mercaptoethanolcysteamine, while the order of relaxant potency (ED₅₀ of phase B) was DTT>cysteamine2-mercaptoethanol. GSSG and cystamine mainly produced relaxation, which corresponded to phase B. The phase C contraction was specific to the reduced forms of thiols, except for GSH, which produced only relaxation. The participation of endothelial cells was not essential for the contracting or relaxing effects of the thiol compounds. The phase C contraction was depressed by W-7, a calmodulin antagonist, while phase A was not. Therefore calmodulin-dependent protein kinases may participate in phase C, not in phase A.     

Le rein intervient-il dans l'homéostasie de la pression artérielle?

Summary Although vasoconstrictor properties have been clearly demonstrated in the venous renal blood after renal ischemia, we have not been able to detect such properties after hypotension in the carotid sinuses or after bleeding in the dog.     

The site of gating in the ventricular conducting system of rabbit, dog and monkey hearts

The longest action potential durations of the ventricular conducting system were found at about two thirds of the distance along each false tendon in dog and monkey hearts. In the rabbit heart, this area which corresponds to the gating mechanism - was found in the middle part of the bundle branches; therefore the number of gates is much smaller in the rabbit than in other 2 species.     

Atrial natriuretic factor in hypovolemic tachycardia

Atrial natriuretic factor (ANF) is released in response to many stimuli which increase right atrial pressure. Following hemorrhage pigs lowered their atrial pressures, developed a tachycardia and increased ANF levels. Electrical pacing increased heart rate and ANF levels. There is a stimulus to ANF release other than atrial stretch, probably heart rate.     

Atrial natriuretic factor in hypovolemic tachycardia

Summary Atrial natriuretic factor (ANF) is released in response to many stimuli which increase right atrial pressure. Following hemorrhage pigs lowered their atrial pressures, developed a tachycardia and increased ANF levels. Electrical pacing increased heart rate and ANF levels. There is a stimulus to ANF release other than atrial stretch, probably heart rate.     

The site of gating in the ventricular conducting system of rabbit,dog and monkey hearts

Summary The longest action potential durations of the ventricular conducting system were found at about two thirds of the distance along each false tendon in dog and monkey hearts. In the rabbit heart, this area—which corresponds to the gating mechanism—was found in the middle part of the bundle branches; therefore the number of gates is much smaller in the rabbit than in the other 2 species.Acknowledgements. We wish to thank F. Pezziardi and P. Guiraudou for their technical assistance.     

Etude, à l'aide de microsphères,de la distribution de l'irrigation carotidienne chez le rat

Summary The carotid blood distribution has been evaluated using radioactive microspheres in 13 regions of the head and in 10 cerebral structures of rats, and the intracerebral distribution of blood has been studied comparatively after injection of microspheres into the left cardiac ventricle or into the internal carotid artery. The principal results indicate that the cerebral tissue is not supplied by the external carotid blood, whereas about 30% of the internal carotid blood goes to the brain, and that the pontomedullary region receives its blood mainly from the vertebral artery.

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Travail réalisé avec l'aide d'un Contrat de Recherche de la Caisse Nationale de l'Assurance Maladie des Travailleurs Salariés.     

Mediation by nitric oxide of neurally-induced human cerebral artery relaxation

Human cerebral artery strips relaxed in response to non-adrenergic, non-cholinergic vasodilator nerve stimulation by electrical pulses or nicotine. The relaxation response was abolished by treatment with N^G-nitro-L-arginine, a nitric oxide synthase inhibitor; the inhibitory effect was reversed by L-, but not D-, arginine. Nitric oxide-induced relaxation was unaffected. These findings support the hypothesis that nitric oxide plays a crucial role, possibly as neurotransmitter, in transmitting information from vasodilator nerve to smooth muscle in human cerebral arteries.     

Influence of sodium balance on atrial natriuretic factor in rats with one-kidney,one-clip renal hypertension

Summary The influence of sodium intake on the gene expression and circulating levels of atrial natriuretic factor (ANF) was investigated in unanesthetized rats with one-kidney, one-clip renal hypertension. After clipping, the rats were maintained for 3 weeks either on a salt-deficient (n=11) or a regular-sodium diet (n=10). Animals which had received the regular-sodium diet exhibited significantly higher ANF mRNA levels in their right and left atria than salt-restricted animals, whereas there was no significant difference in plasma ANF levels.     

Vitamin D receptors in heart: effects on atrial natriuretic factor.

We report that receptors for vitamin D exist in distinct regions of the heart in female and male mice, predominantly in the right atrium where most of the cardial atrial natriuretic peptide (ANF) is produced. Tritiated 1,25-dihydroxyvitamin D3 (1,25-D3, vitamin D, soltriol) and ANF are colocalized in nuclei and cytoplasm respectively in identical cardiomyocytes. Changes of ANF tissue and blood levels under dietary deficiency and treatment with 1,25-D3 suggest direct genomic actions of vitamin D on myoendocrine cells of the atrium for the regulation of ANF manufacture and secretion. These results were obtained by combining thaw-mount autoradiography with immunocytochemistry using tritiated 1,25-D3 and an antibody against rat ANF. This antibody was also used in a radioimmunoassay to determine atrial natriuretic factor in plasma, atria and ventricles of normal or vitamin D-deficient mice.     

Influence of sodium balance on atrial natriuretic factor in rats with one-kidney, one-clip renal hypertension

The influence of sodium intake on the gene expression and circulating levels of atrial natriuretic factor (ANF) was investigated in unanesthetized rats with one-kidney, one-clip renal hypertension. After clipping, the rats were maintained for 3 weeks either on a salt-deficient (n = 11) or a regular-sodium diet (n = 10). Animals which had received the regular-sodium diet exhibited significantly higher ANF mRNA levels in their right and left atria than salt-restricted animals, whereas there was no significant difference in plasma ANF levels.     

L'aorte de l'embryon de poulet: histogénèse,cultures organotypiques,stimulations expérimentales

Summary The authors studied the structure of the aortic wall of chick embryos during embryonal development and after hatching up to the age of 1 month. The typical morphology appears on about the seventh day of incubation; it is established on the twelfth day and it does not change afterwards, there is only an increase in the relative quantities of its morphological components. The aorta is of muscular type in its caudal half, while its cranial half is elastic. The cultures of the elastic cranial half and of the muscular caudal half gave the same results already obtained from the explantation in vitro of elastic arteries (anonyma and pulmonary arteries) and of muscular arteries (carotid).

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Ces recherches ont été faites grâce à un subside du Fonds National Suisse de la Recherche scientifique et de la Fondation E. Barell de la Maison Hoffmann-La Roche SA, Bâle.     

Demonstration of vascular redistribution after carotid clamping in rats

Summary in Long Evans rats, the vertebral arteries supply only the brain stem. Simultaneous application of clamps to both carotid arteries results in a considerable fall of cerebral blood flow and eventually death. If an interval of about 4 days is allowed between the clamping of the 2 carotids, redistribution of blood flow takes place. Owing to this mechanism, 50% of the rats survive with a satisfactory restoration of cerebral blood flow.