Pulsatile Organs Research Articles

Circulatory organs of Diplura (Hexapoda): the basic design in Hexapoda?

The circulatory systems of Campodea augens and Catajapyx aquilonaris (Hexapoda: Diplura) have been examined by means of light and electron microscopy. Hemolymph flow has also been investigated in vivo. Both species share features that deviate conspicuously from the common textbook design of the insect circulatory system: (i) antennal vessels connected to the anterior end of the dorsal vessel; (ii) presence of a circumoesophageal vessel ring in the head; (iii) a bidirectional flow within the dorsal vessel, made possible by intracardiac valves; (iv) posterior end of the dorsal vessel tube opens into a caudal chamber connected to cercal vessels (in Campodea) or to cercal channels (in Catajapyx); (v) dorsal diaphragm barely realized, ventral diaphragm absent altogether, and (vi) legs without specific organs serving hemolymph circulation. Comparative analysis has revealed that these characters in Diplura represent the most plesiomorphic condition in the circulatory organs of all extant Hexapoda. In the basic evolutionary lineages of insects, some organ components have been lost and the peripheral vessels decoupled from the dorsal vessel; as a result, autonomous accessory pulsatile organs have evolved to supply hemolymph to long body appendages and a unidirectional hemolymph flow mode prevailed within the dorsal vessel.

Contributions to Physiology of the Antenna–Heart in Periplaneta americana (L.) (Blattodea: Blattidae)

An accessory pulsatile organ of an open circulatory system in insects supplying the antennae with haemolymph was investigated. The rhythm of this so-called antenna–heart is generated by a myogenic automatism and can be neuronally influenced via the nervus cardioantennalis. The action potentials of the muscle fibres show typical pre-depolarization and mostly no overshoot. A specific membrane resistance ( R m) of about 660 Ω cm −2 was calculated for the fibres. Some electrical coupling between the muscle fibres is presumed for synchronization of any myogenically triggered heart beat which could actually be proved experimentally by current injection in the antenna–heart. However, intercalated disks or gap junctions could not be found. Nevertheless, a good coupling factor ( U 2/ U 1) between all fibres was demonstrated by parallel recordings and can be well described by a conductance model according to fibre topology.

Immunochemical identification and expression of allatostatins in the gut of Diploptera punctata

Dip-allatostatins are a family of related neuropeptides in the cockroach Diploptera punctata that were identified originally on the basis of their ability to inhibit juvenile hormone biosynthesis by corpora allata. These peptides were subsequently also found to inhibit myogenic and proctolin-induced contractions of the cockroach hindgut. Dip-allatostatin immunoreactive material is distributed in several sites within the brain, subesophageal and ventral ganglia and in nerves to the antennal pulsatile organ and hindgut muscles. We have demonstrated here that Dip-allatostatin immunoreactivity is also found in the proctodeal innervation and endocrine cells of the midgut. The endocrine cells which are distributed unequally in different regions of the midgut are also sites of Dip-allatostatin mRNA synthesis. The quantity of Dip-allatostatin immunoreactive material within and released from the gut was assessed by ELISA and RIA. The changes in Dip-allatostatin content in midgut and hindgut extracts during the first 8 days of the reproductive cycle, paralleled, to some degree, the changes noted previously in brain. Our data suggest that the midgut may be another source from which Dip-allatostatins are released into the hemolymph and this release may be regulated, in part, by nutritional status.

Mechanism of beat reversal in semi-intact heart preparations of the blowfly Phormia regina (Meigen)

The blowfly pulsatile organ is a tubular vessel consisting of an abdominal heart and a thoracocephalic aorta. Its activity consists of the regular alternance of a fast phase with a slow phase at higher and lower beating frequencies, respectively. In adult Phormia blowflies the fast and slow phases are triggered by separate pacemakers at the abdominal and cephalic vessel endings, respectively. Owing to the position of the pacemakers, impulses propagate forwards along the vessel during the fast phase and backward during the slow phase. Accordingly, haemolymph flows to the head during the fast phase and to the abdomen during the slow phase. Interspike interval and conduction velocity decrease, while spike duration and risetime increase, from the beginning to the end of the fast phase, together with the emptying of the vessel compartment where it is generated. Prevention of systolic emptying of abdominal heart compartments at the beginning of the fast phase abolishes phase alternance. Possible stretch sensitivity of the Phormia myocardium accounts for this result.

Effect of allatostatin and proctolin on antennal pulsatile organ and hindgut muscle in the cockroach, Diploptera punctata

Diploptera punctata allatostatins are brain neuropeptides that inhibit juvenile hormone synthesis by corpora allata. They also occur in nerves of many organs other than corpora allata. The distribution of allatostatins in, and the effect of allatostatins on two other organs, antennal pulsatile organ and hindgut, are demonstrated here. Allatostatin I-like immunoreactive material is present in cells of subesophageal and terminal abdominal ganglia; these ganglia are known to contain the cells that project to antennal heart nerve and proctodeal nerve, respectively. Electron micrographs of both organs show nerve terminals with allatostatic immunoreactive granules along with terminals containing nonimmunoreactive granules. Immunoreactive neurosecretory granules are about 200 nm in largest dimension. In the antennal pulsatile organ, profiles of the nerve terminals are larger in the ampullar wall than in the muscle; in hindgut the terminals with immunoreactive granules are associated with the muscle net below the circular muscle. Hindgut responded to allatostatins I and IV with a dose-dependent decrease in amplitude and frequency of contraction that was reversible, with the threshold concentration for response between 10(-8) and 10(-7) M. In contrast, pulsatile organ muscle showed no such change with either allatostatin at 10(-7)-10(-4) M. However, both organs responded to proctolin with increased amplitude and frequency of contractions. Allatostatins I and IV inhibited the proctolin-induced increase of hindgut contraction, whereas no such effect was seen in antennal pulsatile organ muscle. Extract of antennal pulsatile organ muscle showed proctolin-like bioactivity that comigrated with authentic proctolin on three sequential HPLC systems.

Wing-hearts in Mecoptera (insecta)

The accessory pulsatile organs for hemolymph circulation in the wings of 7 Mecoptera species were investigated by means of serial semi-thin sections, SEM and TEM. The wing-hearts are located in the dorsal meso- and metathorax, and have no connection to the aorta. Each wing-heart consists of a small hemolymph chamber formed above by the convex scutellum, and below by a horizontal muscular diaphragm. The chamber is connected to the posterior wing veins by a cuticular tube on each side of the body. The diaphragm (10–15 μm thick) is convex in cross-section and consists of transversely extended muscle fibers. Their ultrastructure reveals typical characters of myocardial and other visceral muscle fibers. The diaphragm muscle is innervated by a pair of thin nerves originating from the thoracic ganglion of each corresponding segment. The diaphragm is held in a convex position by numerous elastic strands (2 μm in diameter), which extend through the wing-heart lumen between the scutellum and the diaphragm. The diastolic phase of the wing-heart is caused by contraction of the diaphragm muscle fibers. Thus, the diaphragm flattens and hemolymph is drawn from the posterior wing veins. The systolic phase is caused by the elasticity of the suspending strands after relaxation of the muscle fibers. The elastic strands pull the diaphragm back into convex position and hemolymph is expelled out of the scutellum lumen into the thorax cavity through a valvular opening on the anterior side. The hemolymph flow from the posterior wing base to the scutellum lumen, was visualized by staining the hemolymph. In Panorpa communis the volume of the wing-heart lumen measures 1.6 × 10 −2 mm 3 in the mesothorax, and 1.2 × 10 −2 mm 3 in the metathorax. Each heartbeat transports a maximum of 65% of these volumes. The pumping frequency was 78 ± 20 beats per min, registered with a non-invasive photo-optical method in restrained animals. Corresponding pulsating movements occur as a passive phenomenon of wing-heart activity in a distinct area of the wing base. Only minor differences were found in the construction of wing-hearts among the investigated species, except for Boreus hyemalis, which lacks these accessory circulatory organs. The functional morphology of the wing-hearts in Mecoptera is compared with that of other Holometabola and aspects of the evolution of these organs are discussed.

Allatostatins in the nerves of the antennal pulsatile organ muscle of the cockroach Diploptera punctata.

The presence of allatostatins in the nerves of the antennal pulsatile organ muscle of the cockroach Diploptera punctata was confirmed by immunocytochemistry, bioassay, and HPLC. Immunocytochemical reactivity with monoclonal antibody against allatostatin I showed strong allatostatin immunoreactivity in the antennal heart nerve which innervates this muscle with varicosities along the muscle fibers and in the insertion of the muscle on the pulsatile ampullae. Bioassay of Sep-Pak purified muscle extract demonstrated inhibition of juvenile hormone synthesis by corpora allata in vitro. A dose-response curve showed maximum inhibition of juvenile hormone synthesis was achieved with 10-20 pulsatile organ muscle eq/corpora allata, and 50% inhibition achieved with an estimated 2.6 pulsatile organ muscle eq. Two successive HPLC separations of the Sep-Pak purified extract yielded bioactive fractions corresponding to the elution times of the five known allatostatins.

A new method for study of normal lens developmentin vitro using pulsatile delivery of PDGF or EGF in HL-1 serum-free medium

A new culture method was used to study increases in wet and dry weight and soluble protein during normal development of the transparent lens. Seven different media with more than ten different additives were tested for their effects on cultured lens transparency. In vivo, rat lenses increased 53% in soluble protein content between 3 and 5.5 days of age. Only HL-1 serum-free medium containing 15 micrograms/ml insulin plus 1-2 ng/ml BB platelet-derived growth factor (PDGF), or 5-7 ng/ml epidermal growth factor (EGF) allowed similar growth in vitro, during the same time period. Normal lens growth occurred in culture when fresh medium was delivered to lenses as a pulse every 4-6 hours. Lenses decreased in dry weight and soluble protein content, and became opaque when the same medium was delivered continuously. Lenses increased only 26% and 32% in soluble protein content when delivered pulses of HL-1 medium containing BB PDGF or EGF in the absence of insulin. We suggest that pulsatile delivery of medium containing insulin and PDGF or EGF stimulates lens growth during development in vitro. This pulsatile organ culture system is presented as a new approach for studying the effects of growth factors on cell proliferation, differentiation, and receptor regulation in a developing tissue.

Tissue-specific expression of the 79B actin gene during Drosophila development

We report temporal and tissue-specific patterns of expression of the 79B actin gene in Drosophila. The pattern of accumulation of 79B actin transcripts was determined and compared to the expression of a 79B actin promoter fused to the Escherichia coli β-galactosidase reporter gene. This chimeric gene contained approximately 4 kb of 5′ flanking DNA from the 79B actin gene. We found that β-galactosidase activity in transformants was localized in the same tissues and possessed the same developmental timing as the transcripts of the 79B actin gene. Expression is limited to tubular-type muscles found predominantly in the thorax and leg, including the direct flight muscles, pleurosternal muscles, and muscles of the various leg segments. In addition, the 79B actin gene is expressed in muscles which support the head and abdomen, in the scutellar pulsatile organ, and in abdominal muscles which are present only in male flies.

Antagonism between haemolymph transport and tracheal ventilation in an insect wing (Attacus atlas L.)

1. The interrelations between haemolymph transport and tracheal ventilation in the wings have been analyzed in resting giant silk moths,Attacus atlas L., with repect to the oscillating haemolymph supply of the body. 2. Direction and relative intensity of haemolymph flows in the wing veins are recorded simultaneously with pulse activity of the mesotergal pulsatile organ (PO) by means of contact thermography. 3. The condition of tracheal distension and the haemolymph content in the wing veins are examined by light microscopy and scanning electron microscopy after rapid freeze fixation at specified times during the pluse periods and the pauses of the PO. 4. Haemolymph is periodically sucked out from all wing veins by the PO mainly during reverse pulse periods of the heart and is transported into the abdomen. Haemolymph returns into all wing veins after the first 10 to 25 pulses of the forward pulse period of the heart throughout the pulsation pause of the PO. 5. By removing haemolymph from the wing veins, the POs induce a compensatory increase of tracheal volume and thus bring about wing inspiration. Owing to their elasticity the wing tracheae act as antagonists to the POs, sucking haemolymph back into the wing haemocoele in the course of expiration. 6. Cross-sectional tracheal elasticity is based on coiling of the taenidia along thetransverse axis of the wing tracheae which is superimposed on the normal longitudinal helical arrangement. 7. The functional advantage of haemolymph oscillation and the possible distribution of this supply mechanism in insect wings are discussed.

Oscillating haemolymph ?circulation? in the butterflyPapilio machaon L. revealed by contact thermography and photocell measurements

1. Pulsing and streaming of haemolymph in the heart, aorta and perineural sinus of unrestrained, unnarcotizedPapilio machaon L. (Lepidoptera, Papilionidae) were studied. The interrelationships between heart activity, abdominal movements and activity of thoracic pulsatile organs in haemolymph transport were examined and the indirect effects of these activities on tracheal ventilation of the thorax evaluated. 2. A thermistor technique was developed to record haemolymph movements by their convective and conductive cooling effects at the cuticular surface of insects. In addition, the direction of pulses and of haemolymph flow was determined from temperature measurements, utilizing the temperature gradient along the body axis of basking butterflies. 3. The direction of heart peristalsis changes periodically and is coordinated with abdominal length changes which were recorded using a photocell. Abdominal expansion is accompanied first by a pause and subsequently by reverse beating of the heart. Abdominal expansion may play a leading role in backward haemolymph transport and cause periodic ventral haemolymph backflow through the perineural sinus. Such backflow is most vigorous during heart pauses. The rhythmic undulatory movements of the ventral diaphragm give rise to only slight thermal convective effects. 4. The oscillation of haemolymph between thorax and abdomen is documented on the basis of changes in thermal conduction of the thorax. The significance of periodic haemolymph volume reduction in the thorax for tracheal ventilation is discussed with special regard to the role of heartbeat reversal. 5. During the forward heart pulse periods the abdomen performs volleylike ventilatory movements. These do not cause streaming of haemolymph in the thoracic haemocoel, which at this time is shut off from the abdominal haemocoel by a valve mechanism. This valve, situated in the anterior abdomen, was examined histologically and by scanning electron microscopy. 6. The activity of the lateral thoracic pulsatile organs is regularly interrupted by pauses which occur most frequently during the second half of the heart's forward pulse period. The function of the pulsatile organs is discussed in relation to changing thoracic haemolymph content.

NervousVersusNeurohormonal Control of Insect Heartbeat

Recording semi-isolated insect heartbeat at one time was an art only to be attempted by the most patient of research workers. Thanks to modern advances in biomedical instrumentation, insect heartbeat measurement by impedance conversion and contact thermography allows not only heartbeat recordings, but recording of accessory pulsatile organs and diaphragm movements. The characteristic heartbeat patterns as recorded from adult insects vary enormously from very regular in orthopteroids to highly irregular in Diptera. Pupal stages in holometabolous insects are characterized by a heartbeat which appears to have little or no nervous influence and is punctuated by cessation for periods up to several hours in some insects. The controversy over nervous and/or hormonal control of insect heartbeat has never been completely resolved. There is now a good deal of evidence for nervous control of the heartbeat of Dipteran adults, Lepidopteran adults, Orthopteran nymphs and adults, Dictyopteran nymphs and adults, and Hymenopteran adults. The evidence of hormonal control of heartbeat remains inferential, and is based mostly on the responses of semi-isolated heart preparations. One of the most important events in recent years in this field has been Brian Brown's elucidation of Proctolin in cooperation with Alvin Starratt in Canada. Proctolin is a suspected neurohormone or neurohumor of the proctodeum which may also be used to regulate heartbeat in insects.

Heat exchange in relation to blood flow between thorax and abdomen in bumblebees

1. The narrow passage within the petiole between thorax and abdomen is anatomically constructed so that counter-current exchange should retain heat in the thorax despite blood flow to and from the cool abdomen. 2. However, the counter-current heat exchanger can be physiologically circumvented. Exogenously heated bumblebees prevented overheating of the thorax by shunting heat into the abdomen. They also regurgitated fluid, which helped to reduce head temperature but had little effect on thoracic temperature. 3. Temperature increases in the ventrum of the abdomen occurred in steps exactly coinciding with the beats of the ventral diaphragm, and with the abdominal 'ventilatory' pumping movements when these were present. The ability to prevent overheating of the thorax by transport of heat to the abdomen was abolished when the heart was made inoprative. 4. At low thoracic temperatures the ventral diaphragm beat at a wide range or rates and with varying interbeat intervals, while the heart beat at a high frequency relative to the ventral diaphragm, but at a very low amplitude. However, when thoracic temperature exceeded 43 degrees C the amplitudes of both were high, and the interbeat intervals as well as the beating frequencies of the two pulsatile organs became identical in any one bee. Furthermore, heated bees engaged in vigorous abdominal pumping at the same frequency as that of their heart and ventral diaphragm pulsations. 5. The results indicate that the anatomical counter-current heat exchanger is reduced or eliminated during heat stress by 'chopping' the blood flow into pulses, and the blood pulses are shunted through the petiole alternately by way of a switch mechanism.

Heartbeat reversal and its coordination with accessory pulsatile organs and abdominal movements in lepidoptera

Haemolymph in certain Lepidoptera at rest is periodically transported from the anterior body to the abdomen and reversed by the coordinated activity of the heart, the accessory pulsatile organs and the abdomen. This oscillatory haemolymph transport is suggested to support haemolymph exchange and air ventilation in the anterior body and wings.

Autolysis in axon terminals of a new neurohaemal organ in the cockroach Periplaneta americana

An ultrastructural investigation showed that there was a neurohaemal organ in the wall of the ampulla of the antennal pulsatile organ. The neurosecretory axon terminals occurred singly or in small groups rather than closely packed together as in other neurohaemal organs. All axons contained the same type of neurosecretory granule. The granules had varying electron density and a diameter in the range 1000–2500 Å. Some terminals contained small, elliptical, electron-transparent vesicles and the axolemma was apposed to the stroma. Other terminals were large and enveloped by glial tissue and the contents of the terminals exhibited varying degrees of autolytic degeneration. Autolysis was characterized by the occurrence of dense bodies and multilaminate bodies which enclosed mitochondria and neurosecretory granules. It was suggested that the neurosecretory material affects antennal function.

Rôle des organes pulsatiles thoraciques et du cœur pendant l'émergence et l'expansion des ailes des lépidoptères

Electrograms of the thoracic pulsatile organs and of the heart during emergence and expansion of the wings have been made. The mesotergal and metatergal organs function in a similar way: active periods are interrupted by short periods of rest, but the two organs contract with different but apparently independent rhythms. During emergence and expansion, the rate of contraction of the pulsatile organs increases twofold, and the resting periods disappear during the entire period of expansion of the wings. When the wings are removed or cut short, the activity of the pulsatile organs is inhibited.

Vascular injury of cadaver kidney: Detection with xenon-133 technique

Bilateral nephrectomy was performed on the cadaver of a patient who died from a ruptured cerebral aneurysm. One kidney was preserved with pulsatile perfusion and evaluated with a 133Xe (radioactive Xenon) washout study while the kidney was maintained on the pump. The 133Xe washout study revealed that 60 per cent of the renal mass supplied by the main renal artery was not perfused because of a vascular injury. The remainder of the renal mass, which was perfused through a polar artery, had an abnormal intrarenal distribution of the plasma flow. This kidney was not transplanted. The other kidney was immediately transplanted without pulsatile perfusion. Renal arterial thrombosis occurred in the immediate period after transplantation, and the kidney was removed. This case demonstrates the importance of the 133Xe washout study during pulsatile organ preservation in evaluating kidneys of marginal quality.

Experimental studies in renal preservation (author's transl)

Using hypothermia, mechanical pulsatile organ perfusion and control of increased pressurekidneys of miniature swine could be conserved for up to 48 h. Composition of the perfusion solution and rate of

THE PULSATILE ORGAN IN THE TIBIA OF TRIATOMA PHYLLOSOMA PALLIDIPENNIS

AbstractThe pulsatile organ, or "accessory heart," in the tibia of Triatoma consists of a membrane which divides the femur and tibia into a series of sinuses, a pulsatile muscle which propels the haemolymph through the sinuses, and a valvular membrane, which imposes unidirectional flow on the system. A possible innervation of the muscle is described, and simple experiments involving nerve stimulation demonstrate that the pulsatile muscle is under nervous control. Using partially isolated preparations of the pulsatile organ, it has been shown that the organ responds to dopamine and serotonin, but fails to respond to acetylcholine. The pulsatile muscle therefore resembles visceral muscle rather than skeletal muscle.

Some aspects of the internal anatomy of the leafhopper Agillia constricta (Homoptera: Cicadellidae).

The gross anatomy of the alimentary canal and malpighian tubules of Agallia constricta (Van Duzee) is described, as well as the histology of their various regions. Rickettsia-like microorganisms and carbonates were found in the midgut. Each salivary gland, consisting of a principal 4-lobed gland and an accessory gland, contains 5 different types of acini. In the male reproductive system there are a pair of testes, each with 6 follicles, a pair of vasa deferentia, and a median ejaculatory duct, plus a pair of accessory glands. Each ovary of the female system is made up of 6 ovarioles, each consisting of terminal filament, germarium, vitellarium, and pedicel. The calyx connects the ovarioles with the lateral oviducts and these open to a common oviduct leading to the genital chamber; 2 small accessory glands and a paragenital gland are present. The central nervous system comprises 4 ganglionic masses: the brain, the subesophageal ganglion, the prothoracic ganglion, and the fused ganglia of mesothorax, metathorax, and abdomen; nerves from these various ganglia innervate the different organs. The circulatory system consists of a dorsal vessel, formed by a 7-chambered heart in the abdomen and an aorta extending from the heart into the head. What appear to be accessory pulsatile organs occur in the dorsal part of the abdomen and in each tibia near the femur. Each of the 2 mycetomes is an isolated structure in the anterior part of the abdomen, appressed laterally to the integument. The fat-body, surrounding all organs, is present in the head, thorax, and abdomen, but is most plentiful in the abdomen.