Hemolymph Pressure Research Articles

Heart and circulatory functions in a spider (Eurypelma californicum): the effects of hydraulic force generation

In the tarantulaEurypelma californicum, the relationships between heart activity, circulation and the generation of hydraulic pressure for locomotion were studied. Several new techniques were employed. Mean resting heart rate was 21 beats min−1 rising to 90 beats min−1 after burst activity. Decay time to resting rates was related to the increase of heart rate. Post-recovery resting rates were usually elevated in comparison with rates after very long resting periods. A relative measure of heart amplitude was obtained. Four distinct patterns could be distinguished: (i) regular beats; (ii) short-term fluctuations of amplitude within a few heart beats; (iii) a slow rhythmic change of heart/pericardium filling, and (iv) non-periodic, stronger amplitude changes during periods of activity. During locomotion, heart rate rises with maximum rates often reached only minutes after the onset of activity. The rising phase is often characterized by irregularities and a reduction of heart amplitude. Prosomal hemolymph pressure in resting, restrained animals was 41±19 Torr, rising to ca. 90, and 217±48 Torr during walking and fast sprints, respectively. Values in unrestrained spiders were similar. Opisthosomal hemolymph pressures were ca. 20 Torr in resting animals, rising to 40–60 Torr during locomotion. Opisthosomal volume changes were measured. A small volume of hemolymph moved from the prosoma to the opisthosoma at the onset of locomotion, but following activity this volume quickly returned to the prosoma. The simultaneous measurement of carapace depression, opisthosomal volume changes and hemolymph pressures, and heart activity revealed the relationship between circulation and hydraulic force generation. The direction of hemolymph flow was also studied. In non-active animals, the heart occasionally changes its main pumping direction. During locomotion, hemolymph flow from the heart to the prosoma is often reduced or stopped. With a slight delay, hemolymph flow to the opisthosoma is increased. The critical pressure at which prosomal perfusion from the heart is halted is 50–70 Torr. It is concluded that anterior and posterior circulations are separate: hemolymph returning from the prosoma passes only through the anterior lungs, while hemolymph returning from the opisthosoma passes through the posterior lungs.

Effects of diets on osmotic pressure of hemolymph and egg juice in the silkworm, Bombyx mori

Effects of diets on osmotic pressure of hemolymph and egg juice in the silkworm, Bombyx mori

Observations on the physiology and integumentary structure of the Antarctic pycnogonid Decolopoda austratis

The giant Antarctic pycnogonid Decolopoda australis Eights takes up oxygen by diffusion across the integument, particularly of the legs. The circulatory system is feeble and haemolymph pressure changes are induced by leg movements during locomotion rather than by cardiac action. Heart rate is about30–40 beats min‐1 between 1 and 5 °C; it becomes irregular above 5 °C and ceases (reversibly) at6–7 °C.The integumentary structure appears to facilitate gaseous exchange. Although the cuticle (c. 200 μm thick) is chitinous, it is perforated (over 35% of the internal surface) by circular/ ellipsoidal tissue‐filled pits which are separated from the external environment by thin layers of chitinous cuticle no more than4–6 μm thick. The pits occur in all parts of the body and appendages (except arthrodial membranes). It is suggested that the primary function of the tissue within the pits is to form a route for gaseous diffusion, which bypasses the relatively thick impermeable chitinous layers of the rest of the cuticle. Calculations suggest that the pits reduce resistance to gaseous diffusion by about 90%.To function as a respiratory surface, the general body surface has to be kept clean. The cleaning action of the ovigers appears to be effective, except in the regions between the contiguous lateral processes of the body where detrital material accumulates.

Posteclosion behavior of the flesh fly, Sarcophaga crassipalpis: A comparison of wild‐type and unicorn mutants

AbstractNewly emerged flies go through a stereotypic behavioral pattern of walking, grooming, abdomen contraction (pulsing), and active uptake of air (pumping). These behavioral activities can be readily distinguished on the basis of hemolymph pressure changes. Wild‐type flies and a unicorn mutant that fails to properly retract its ptilinum show identical patterns of posteclosion activity. However, a portion of the unicorns do not fully expand their wings and abdomen. Such flies are missing only the pumping component of the normal behavioral repertory, thus implying that pulsing and pumping are independently controlled.

Effect of juvenile hormone on the autonomic nervous system

The effects of juvenoids on the autonomic nervous system, which controls certain physiological functions by means of special extracardiac pulsations in hemolymph pressure, have been studied in pupae of the mealworm, Tenebrio molitor. Prolonged tensiometric monitoring of the hemolymph pressure changes revealed that the extra-pupal development that had been caused by juvenoids evoked unusual reappearance of prepupal pattern of extracardiac pulsations. By contrast, the specific pharate adult types of the pulsations completely disappeared. The functioning of the autonomic nervous system was aberrant or incomplete during an unsuccessful extra-pupal ecdysis. It is suggested that malfunction of the autonomic nervous system in the extra-pupal instars may be the reason for the ecdysial failures associated with the use of juvenoids.

Haemolymph pressure in certain cirripedes

Haemolymph pressure has been measured in the mantle sinus of several balanomorph barnacles and the peduncular sinus of two lepadomorph species. The absolute pressure of balanomorphs was found to be similar to that recorded for other crustaceans. The absolute pressure of lepadomorphs was much higher than that in balanomorphs. Regular puls̀e pressures were synchronized with body movements, cirral extension and valve movement. It is concluded that haemolymph is circulated by general body movements even when the opercular/capitular valves are closed.

Electrophysiological and anatomical identification of the peripheral axons and target tissues of Aplysia neurons R3-14 and their status as multifunctional, multimessenger neurons

The giant neurons R3-14 in the parietovisceral ganglion of Aplysia, originally proposed to be a homogeneous group of neuroendocrine cells, are likely candidates for a multifunctional and multiple messenger status. The studies reported here suggest that individual R3-14 giant neurons not only innervate specific target tissues but appear to operate more autonomously than previously thought. Identified members of the group were traced into peripheral tissues by electrophysiological, autoradiographic, and intracellular cobalt staining techniques. Five neurons (numbered R6, R7, R8, R11, and R14) were identified on the basis of their unique patterns of axonal projections. R6 innervates the ganglionic artery and pericardial area; R7 and R8, the heart; R11, the kidney; and R14, a large number of vascular tissues. The wide distribution of R3-14 terminals innervating a variety of vascular tissues indicates that several general and local aspects of circulatory physiology are likely to be regulated by these neurons. R3-14 contain the free amino acid glycine, a putative neuromodulator that potentiates cardiac and vascular smooth muscle contraction and several small peptides of unknown, but probably neurohormonal, function. A model is proposed in which R3-14 release glycine to modulate local (e.g., hemolymph pressure and distribution) cardiovascular performance and, indirectly, metabolic homeostasis as well.

Cholinergic control of extracardiac pulsations in insects

The autonomic nerve system which controls extracardiac pulsations of hemolymph pressure appears to be quite susceptible to cholinesterase inhibitors (physostigmine, organophosphorus insecticides). In pupae ofTenebrio molitor L. andGalleria mellonella L., the treatment induced large peaks in hemolymph pressure (over 4 kPa). The peaks were repeated at more-or-less constant, 30-s intervals for several hours or days. Removal of the pupal brain neither affected extracardiac pulsations nor influenced the specific responses to the investigated drugs or insecticides.

Pupal ecdysis in flies: Mechanisms of evagination of the head and expansion of the thoracic appendages

The development of pupal thoracic structures from imaginal discs proceeds in three steps: (1) The discs evaginate (evert and unfold to produce the general shapes of the adult structures), (2) the evaginated discs are inflated with haemolymph, and, (3) the inflated structures expand to form their definitive pupal shapes (specific internal components will migrate into these structures and differentiate into adult organs). Evagination of the head and inflation of the appendages is attained by peristaltic abdominal muscular contractions during the ecdysial phase of pupation. Relatively low haemolymph pressure (3.8 Torr) is needed to accomplish this. Morphogenesis of pupal structures is completed during the prolonged period of vigorous muscular activity accompanying the expansion stage. The pressure in the haemocoel reaches a value greater than 15 Torr at this time, being produced by asymmetrical contractions of the abdominal muscles. Swaying lateral movements caused by these contractions seem to be indispensible for extrication of the larval tracheal lining from the spiracles.

Ventilation, Circulation and Their Interactions in the Land Crab, Cardisoma Guanhumi

ABSTRACT Physiological variables for ventilation (scaphognathite frequency, branchial chamber pressure and branchial air flow) and for circulation (heart rate, intracardiac and pericardial haemolymph pressure) were measured in the land crab Cardisoma guanhumi (Latreille). Crabs were studied both in air alone and in air with access to a shallow layer of fresh, brackish or sea water. During complete air exposure, forward scaphognathite beating predominated and reversed scaphognathite beating was very infrequent. Periods of apnoea were rare. When crabs were able to immerse the Milne-Edwards openings to the branchial chambers in water, scaphognathite reversal occurred much more frequently, and most air flow through the branchial chambers was generated by this mode of ventilation. Changes in water salinity had no effect on respiratory patterns. The cyclic variation between forward and reversed scaphognathite beating appears to serve not only to ventilate the branchial chambers with air, but also to flush water through the branchial chambers for non-respiratory purposes such as ion, water and acid-base regulation. Haemolymph pressures were comparatively low (14 mmHg systolic, 6mmHg diastolic). During diastole a pressure gradient of approximately 0·6 mmHg existed between the pericardial space and the heart lumen. Pauses in heart beat were never observed. Circulatory events were closely coordinated with adjustments in ventilation. Reversed scaphognathite beating produced a transient increase in systolic and diastolic haemolymph pressure due to the rise in branchial air pressure acting directly upon the large, haemolymph-filled spaces lining the branchial chambers. A transient bradycardia accompanied this brief rise in central haemolymph pressures. Possible mechanisms for the regulation of haemolymph pressure are discussed.

Influence of ligature and cooling on metabolic adaptability of galleria mellonella larvae

1. 1. Ligature and cooling of Galleria mellonella larvae reared at 30° and 4°C induced changes in oxygen consumption, in the number of native proteins and in the osmotic pressure of haemolymph, as compared to controls. 2. 2. After three days of ligature there was a 13-fold decrease in oxygen consumption. Fifteen days later, the total metabolism increased five times to 990 mm 3 O 2.g −t.hr −1. 3. 3. The ligature induced much higher activity of proteosynthesis in haemolymph of the larvae than cooling did. 4. 4. Fourteen days of ligature resulted in a reduction of osmotic pressure in the haemolymph of the larvae by 25%. 5. 5. Cooling of the larvae induced an increase in the osmotic pressure of the haemolymph. 6. 6. Cooling of the ligated larvae resulted in a reduction of the osmotic pressure of the haemolymph. 7. 7. Use ofjuvenoid R-394 increased the consumption of oxygen in the eighth instar larvae of Galleria melloneila.

A cryofixation study of a subcuticular receptor organ in the antennular tip of the terrestrial isopod, Porcellio scaber Latr. (Crustacea)

The structure of a subcuticular receptor organ in the antennular tip of the terrestrial isopod Porcellio scaber was examined in cryofixed and chemically fixed material. The organ consists of a single sensory cell and two enveloping cells lying beneath an area of soft cuticle. The dendritic outer segment of the sensory cell is unique in that it lies within an extraepidermal space curled around a fingerlike epidermal diverticle. This diverticle encloses an extension of the hemolymph space. The wall of the diverticle is extremely thin. Silver-protein and lanthanum failed to penetrate the overlying soft cuticle. The spatial configuration of the dendrite and cytoskeletal elements within the inner enveloping cell are particularly susceptible to artificial deformation and could only be demonstrated in cryofixed preparations. The structural characteristics suggest the receptor function as proprioceptor sensitive to hemolymph pressure changes.

Recording of haemolymph pressure pulsations from the insect body surface

1. Relative changes in mechanical pressure of insect haemolymph can be directly recorded from the body surface. Semiconductor straingauge transducers sensitive to loads smaller than 1 μg were used to record movements in the nm range. 2. The instrumentation makes it possible to monitor continuously the rhythmic pulsations in haemolymph pressure over periods of several days or weeks. 3. Synchronized recordings with direct hydraulic and indirect contact transducers in one specimen revealed that the contact transducer method could detect the smallest pulsations in haemolymph pressure. 4. The method was applied to various stages of some Coleoptera, Lepidoptera and Diptera during metamorphosis. Hitherto unknown types of pulsations with different frequencies and amplitudes are described. 5. The continuous monitoring of extracardiac pressure pulsations appears to be a suitable method not only for the diagnosis of normal or pathophysiological states, but also for the determination of ecdysial processes and, in particular, for pharmacokinetic studies on the action of insect hormones, drugs or insecticides.

The effects of 20-hydroxyecdysone on haemolymph pressure pulsations in Tenebrio molitor

Changes in haemocoelic pressure have been studied after the injection of exogenous 20-hydroxyecdysone, using a special tensometric method. Application of the hormone before the endogenous peak of ecdysteroid causes an acceleration of the progressive changes in the pulsation pattern. When given during the endogenous ecdysteroid peak, 20-hydroxyecdysone produces a retention of the existing type of pulsation. Also, administration of the hormone after the endogenous peak induces a retardation in the developmental programme of the pulsations. Shortly before ecdysis, the exogenous hormone does not affect the pulsation programme or the ecdysis. These changes may represent an elegant example of a homeostatic function of ecdysteroids in insect development. Involvement of 20-hydroxyecdysone in regulation of the basic haemolymph pressure is discussed.

The Comstock-Kellogg glands in female Schistocerca gregaria: Their eversion and haemocoelic pressure

The glandular pouches of Comstock and Kellogg on the genital chamber of females of Schistocerca gregaria can be everted and displayed by exerting firm pressure on the tip of the abdomen. The glands evert when the ovipositor values are extended and the gland apertures pass the posterior border of the sub-genital plate. This process has not been observed to occur spontaneously in females in this colony. Increasing the pressure in the haemocoel by means of a saline reservoir is effective in causing gland eversion only when pressures in excess of 75 mm mercury are used: these pressures cause abnormal distortion in the insect. Haemolymph pressure monitored in digging and egg-laying females varies only slightly from atmospheric pressure and never approaches the pressures required to enforce gland eversion. Gland eversion is not observed in digging females, but is difficult to observe in females in the act of laying, due to the presence of egg-pod secretion. These observations are discussed in relation to the structure of the pouches and other information concerning their possible functions in the female desert locust.

Oxygen Consumption and Haemolymph Pressure Measurements in Armadillidium Vulgare (Latreille) (Armadillidiidae: Isopoda) During Ecdysis

ABSTRACT Hydrostatic pressure in the haemocoele of Armadillidium vulgare adults ranges between 40 and 185 mm H,O (2.99-13.66 mm Hg), while the oxygen consumption varies from 13.43 μl O2/mg body wt./h in the males to 14.59 μl O2/mg body wt./h in the females. The specific variations in the oxygen consumption rate and the haemolymph pressure during ecdysis in an adult isopod were studied. The significance of these findings is discussed.

Vibration sensitivity of pretarsal slit sensilla in the spider leg

1. The two single slit sensilla on the pretarsus of the spider leg (Cupiennius salei Keys.) are vibration sensitive. Due to their arrangement they are also stimulated effectively by active downward movement of the pretarsus which may result from muscular activity directly or from an increase of the hemolymph pressure (Figs. 1, 2, 3). 2. The slits are not tuned to a restricted frequency range. Their threshold displacement was determined electrophysiologically from 0.01 Hz to 1 kHz and found to be higher than in the slits of the metatarsal organ by roughly two orders of magnitude. The threshold decreases only slightly up to about 40 Hz but much more steeply at higher frequencies. The minimal threshold value for displacement within the tested frequency range was found at 1 kHz and measured 2 × 10−5 cm. The minimal threshold value for acceleration found at 0.01 Hz was 0.3 × 10−9 cm/s2 (Fig. 4a). Thresholds vary with different preset tensions in the cuticle surrounding the slits (Fig. 5). 3. The shapes of the threshold curves are similar for dorsoventral and lateral displacement of the pretarsus (Fig. 4b). Values for lateral displacement are at most 3 dB higher than those for dorsoventral displacement. 4. As in other slit sensilla the frequency response of the pretarsal slits follows a power functiony(f) =fk (Fig. 7). The constantk varies between 0.39 and 0.44, reflecting receptor properties intermediate between those of a frequency-independent amplitude receptor (k = 0) and those of a velocity receptor (k = 1). Beyond 10 Hz the response of the receptor saturates. Phase locking between stimulus and response is observed up to about 100 Hz (stimuli 10 dB above threshold).

Involvement of actin and Na+ -K+ ATPase in urine formation of the freshwater pulmonate Helisoma.

The site and process of urine formation in the renopericardial system of Helisoma have been investigated. Osmotic pressure and protein content of hemolymph from the heart, pericardial fluid from the pericardial cavity, prourine from the kidney sac, and urine from the ureter have been determined. Osmotic pressure is equal in hemolymph, pericardial fluid, and prourine, but less in urine. Protein content is similar in hemolymph and pericardial fluid, but much less in prourine and urine. Hemoglobin molecules are present in hemolymph and pericardial fluid but not in prourine. It is suggested that in Helisoma the kidney sac is the site of prourine formation, and prourine is an ultrafiltrate of hemolymph. The kidney epithelial cells contain 6- to 7-nm microfilaments which react with heavy meromyosin producing unidirectional arrowheads. Numerous actin filaments are present in the vicinity of the lateral cell membranes and basal processes. It is possible that the actin filaments regulate the extracellular spaces for prourine passage. It is postulated that the actin-rich kidney epithelium may generate hydrostatic pressure for ultrafiltration. Na+ -K+ ATPase is located on the luminal side of the kidney epithelium, which may regulate intracellular fluid level of the kidney epithelial cells, and thereby regulate their cell volume. Thus Na+ -K+ ATPase may be involved in the regulation of extracellular spaces in kidney epithelial cells. The enzyme may participate in the production of hyposmotic urine.

A Hormone Effecting Immobilization in Pupariating Fly Larvae

ABSTRACT The haemolymph of 1–2 h old (orange) puparia of Sarcophaga bullata contains a factor (PIF) which immobilizes mature fly larvae, most strongly 6–24 h before pupariation. It has all the properties of a protein: a mol. wt. of between 100000 and 300000 daltons, it is heat labile, non-dialysable, destroyed by trypsin, and precipitated by NH4SO4. It is possibly identical with the anterior retraction factor (ARF) because the activity of both always went hand in hand. Its action seems to be unspecific in cyclorrhaphous flies. Much about PIF has been learned from studying changes in internal haemolymph pressure of larvae injected with PIF before and during pupariation. Its function is probably to shut off muscular activity after the puparium is completed. It may also function in very small dosages at the beginning of pupariation when the activity of the larvae decreases.

Monitoring the course of bacterial infections by hemolymph pressure pulses in insects

Changes in rhythmic pulsations of hemolymph pressure have been continuously monitored from several hours before injection of the pathogenic bacteria until death of the infected Tenebrio pupae. Lethality induced by five different species of entomopathogenic bacteria was associated with specific changes in the hemolymph pressure pattern. During the initial stages of infection (incubation period) the pupae continued to produce regular and synchronized series of normal pulsations. The pathophysiological symptoms of the acute disease became manifested by successive desynchronisation of the frequency and simultaneous depression of the amplitude of the pulsations. This irreversibly proceeded, with species specific modifications, until death of the pupae when all peaks in hemolymph pressure disappeared. Duration of the incubation period was inversely proportional to the injected dose, while the later period characterized by development of the pathophysiological symptoms had more or less constant course in infection with each bacterial species. Certain toxic enzymes, protease and phospholipase C, had similar action on hemolymph pressure pulses. Application of the tensometric method to pathophysiological studies in insects has been discussed.