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.     

The influence of ambient temperature on thermoregulatory responses to intraventricularly injected monoamines in sheep,goats and rabbits

Zusammenfassung Zur Erklärung der Effekte auf die Thermoregulation in Schafen, Ziegen und Kaninchen bei verschiedenen Umwelttemperaturen von intraventrikulären Injektionen von Noradrenalin (NA) und 5-Hydroxytryptamin (5-HT) wurde ein einfaches Neuronenmodell vorgeschlagen. Diese Monoamine entfalten nicht in allen Situationen eine reziproke Wirkung. 5-HT führt zu einem Anstieg des Wärmeverlustes und einer Hemmung der Wärmebildung. NA hemmt sowohl Wärmeverlust wie auch Wärmebildung 19.     

Effects of disodium EDTA on the cardiovascular responses to prostaglandin E1

Zusammenfassung Die Wirkung des Dinatrium-EDTA auf die Kreislaufreaktionen des Prostaglandin E₁ (PGE₁) wurde an narkotisierten Hunden untersucht. Das Ausmass der positiv chronotropen und inotropen Einflüsse des PGE₁ war während der Infusion von EDTA bedeutend geringer als das des PGE₁ vor der EDTA-Gabe. Die Gegenwart oder das Einströmen von Kalziumionen scheint in der pharmakologischen Wirkung des PGE₁ eine Rolle zu spielen.     

The influence of hypertension upon the normal cardiovascular responses to hemorrhagic hypotension and shock

The data suggest that rats genetically inbred to be hypertensive (SHR) are less able to compensate for hemorrhage and shock than their normotensive controls (WKY). Two reasons for this genetic dysfunction are: 1) SHRs seem to depend more on innervated alpha 1 than noninnervated alpha 2 adrenoreceptors for vasoconstriction; and 2) the vascular smooth muscle hypertrophy noted in SHRs may interfere with effective vasoconstriction.     

Influence of repeated prazosin administration on cardiovascular responses in rats and rabbits

Prazosin was injected i.v. at a dose of 50 g/kg every 2 h for 8 h in conscious rats. Its hypotensive action significantly declined. A similar effect was also observed in rabbits pretreated with prazosin (40 g/kg, i.v.) every 1 h for 4 h. In prazosin-treated rabbits, the total peripheral resistance became less responsive to phentolamine stimulation. Repeated prazosin administration abolished its ability to block receptors in a model of anococcygue muscle contraction after noradrenaline (NA) stimulation. The -adrenoceptors in anococcygue muscle exhibited lower pD₂ to NA and lower pA₂ to prazosin in prazosin-treated rats. The results demonstrate that repeated prazosin administration reduces the effectiveness of -adrenoceptors blockers.     

Is the variation in the susceptibility of various species to atherosclerosis due to inborn differences in prostacyclin (PGI2) formation?

Summary Species exhibiting a higher susceptibility to the development of atherosclerosis have a reduced prostacyclin (PGI₂)-generation in the arterial wall, which differs in various parts of the vascular system. As the difference in PGI₂-formation in various diseases is a generalized vascular effect, the changes can be detected in all vessels. This is a very important point for diagnostic purposes in humans.This study was supported by a grant of the «Fonds 600 Jahre Wiener Universität der Kammer der gewerblichen Wirtschaft für Wien».     

Failure of the pineal body of two species of birds (Coturnix coturnix japonica andPasser domesticus) to show electrical responses to illumination

Résumé Dans l'épiphyse de 2 espèces d'oiseaux il n'a pas été possible de démontrer une relation entre le potentiel électrique et les variations d'illumination. On peut en conclure que chez ces oiseaux l'épiphyse n'est pas un photorécepteur dans le sens conventionnel.

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This investigation was supported by National Science Foundation Grant No. GB-5605.     

Polyreactive antibodies in adaptive immune responses to viruses

B cells express immunoglobulins on their surface where they serve as antigen receptors. When secreted as antibodies, the same molecules are key elements of the humoral immune response against pathogens such as viruses. Although most antibodies are restricted to binding a specific antigen, some are polyreactive and have the ability to bind to several different ligands, usually with low affinity. Highly polyreactive antibodies are removed from the repertoire during B-cell development by physiologic tolerance mechanisms including deletion and receptor editing. However, a low level of antibody polyreactivity is tolerated and can confer additional binding properties to pathogen-specific antibodies. For example, high-affinity human antibodies to HIV are frequently polyreactive. Here we review the evidence suggesting that in the case of some pathogens like HIV, polyreactivity may confer a selective advantage to pathogen-specific antibodies.     

EMG responses to capsular stimulation in the human

Riassunto Gli autori studiano la latenza e le caratteristiche elettromiografiche delle risposte muscolari provocate con stimoli capsulari nell'uomo. Le clonie provocate in muscoli in stato di leggera contrazione sono seguite in genere da una fase di rilasciamento muscolare di 50–200 msec di durata.     

Daily variations in pigeon cropsac responses to prolactin

Zusammenfassung Es wird festgestellt, dass die Ansprechbarkeit des Taubenkropfsackes auf Prolactin in Abhängigkeit vom hormonalen Zustand des Versuchstieres von Tag zu Tag verschieden ist.

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Our study was supported by a Public Health Service Research Grant No. 5 R01 AM13400 and a Public Health Service Research Career Development Award No. GM-17, 898, toAlbert H. Meier. The ovine prolactin was a gift of the Endocrinology Study Section of the National Institutes of Health. We thank Dr.P. E. Schilling of the Computer Center at Louisiana State University for making the statistical evaluations.     

Thermo-regulatory responses to hypothalamic heating in dehydrated rabbits

Résumé Chez les lapins déshydratés par privation d'eau pendant 3 jours, on constate la disparition de la polypnée produite par la stimulation thermique de l'hypothalame antérieur, tandis que la réaction vasodilatatrice cutanée est conservée.     

Studies of the differences of osmotic pressure between the aqueous humor and the serum in some species of animals

Riassunto L'autore ha eseguito determinazioni della pressione osmotica dell'U. Acqueo e siero in alcune specie animali col metodo diNiederl e Levy. In tutte le specie animali ha riscontrato sempre un'ipertonia dell'Acqueo rispetto al siero di circa 2m/M.Soltanto nella cavia l'acqueo è leggermente ipotonico in rapporto al siero. L'autore spiega questa eccezione con la deficienza di anioni (cloruri e bicarbonati riscontrata nell'acqueo di cavia).     

Temperature-dependent responses to a developmental gradient in theDrosophila wing

Summary The mutant hairy (h) increases the number of sensillae on theDrosophila wing. This allows us to quantify a gradient that determines the type of sense organ that forms along the third long vein. Temperature significantly shifts the positional responses to this underlying gradient.This research was supported by National Science Foundation grant BSR-8300025. We thank Laura Karcher for the figure.