Circulation in the cephalopod, Octopus Dofleini
Kjell Johansen†, a and Arthur W. Martina
aDepartment of Zoology, University of Washington, Seattle 5, Washington, USA
Received 29 September 1961. Available online 17 March 2003.
Abstract
1. 1. Simultaneous recordings of pressure from the cephalic aorta, the afferent and efferent branchial vessels and the vena cava cephalica have been made in unanethetized, unreastrained cephalopods, Octopus dofleini.
2. 2. The frequency of the systemic heart varied between 8–18 beats/min at a water temperature of 7–9°C. The aortic systolic pressure varied during normal conditions between 45–70 cm of water with a pulse pressure of 20 cm of water. The pressure level in the afferent branchial vessels ranged from 25 to 50 cm of water systolic and about 15 cm of water diastolic pressure. Similar values in the efferent branchial vessels were 10–25 cm of water systolic and 5–15 cm of water diastolic. In the vena cava cephalic the pressure ranged under normal conditions between 0–17 cm of water with a pulse pressure of 3–5 cm of water.
3. 3. The pressure recordings indicate that the ctenidia contract actively in a rhytmic fashion, promoting the propulsion of blood. The pressure changes in the vena cava cephalica are thought to be passively mediated from pressure changes created by the respiratory movements.
4. 4. During exercise there is a marked increased in both pulse pressure and diastolic pressure in the aorta. The heart sometimes showed great acceleration during exercise.
5. 5. Experiments with infusion of sea water into the vascular system demonstrated a capacity for accomodation of large volumes without noteceable disturbance of the general circulation.
6. 6. Pressure recordings in a symmetrical arrangement in the branchial vessel indicate a crucial importance of the nervous system for coordination of activity in the octopus vascular system.
7. 7. The haemodynamics of the cardiovascular system in Octopus dofleini are discussed.
Effects of some drugs on the circulatory system of the intact, non-anesthetized cephalopod, Octopus dofleini
Kjell Johansen†, a and Mervyn J. Huston‡, Department of Zoology, University of Washington, Seattle 5, Washington, USA
Received 5 September 1961. Available online 17 March 2003.
Abstract:
1. The effects of epinephrine, nor-epinephrine, ergotamine, serotonin, acetylcholine, eserine, tyramine and histamine have been studied in the non-anesthetized cephalopod, Octopus dofleini. Simultaneous recordings were made of blood pressure from the aorta, the afferent and efferent branchial vessels and the large vena cava cephalica concurrent with injections of the drugs.
2. Epinephrine and nor-epinephrine both had a depressing effect on the circulatory system. Both drugs caused a retardation in rate of the systemic heart. The initial effect seemed to include a decrease in the resistance of the peripheral vascular bed. The branchial hearts were also decelerated by epinephrine and nor-epinephrine. Pretreatment with dihydroergotamine abolished all effects of a subsequent injection of epinephrine.
3. Tyramine, like epinephrine and nor-epinephrine, caused bradycardia of the systemic and branchial hearts.
4. Acetylcholine had a marked retarding effect on the systemic heart as well as on other rhythmically contractile processes in the octopus circulatory system. To a lesser degree acetylcholine acted as a peripheral vasodilator. Histamine had a short-lasting but marked vasodilatory effect on the peripheral vascular bed.
5. Serotonin invariably caused a stimulation of the systemic and branchial hearts and contractions of the ctenidia.
6. The injection of the drugs demonstrated that the various functional elements in the creatly differentiated vascular system of the cephalopods influence each other via nervous communication.
dwhatley;160585 said:This seems odd. Why would the heart work harder in higher oxygen? I keep thinking oxygen levels may be more important (especially in the hatchlings). I am not sure how it actually plays out but this seems counter to what I would think.Level_Head;160562 said:The hearts still beat in the same synchonized pattern with the nerves cut, and the trio of hearts still increased with temperature and oxygen (more oxygen, faster heartbeats).
In intact octopuses the beat rate is closely related to temperature and oxygen tension, slowing progressively as either falls (Wells, 1979).
The heartbeat of an intact Octopus vulgaris is temperature sensitive, with a Q10 of about 3 over the range 7-27 °C. The hearts are also sensitive to the oxygen content of the seawater bathing them, slowing progressively as this declines; at about 2-5 ppm the beats become irregular, and may stop (Wells, 1979).
Fig. 10 shows the effect of transferring an octopus from seawater at 6-8 ppm O2 to seawater at 2-7 ppm O8 and then returning it to the O2 saturated water. The systemic heartbeat slows within a few seconds of transfer, and picks up again when returned to the oxygen-rich seawater. This animal had both cardiac ganglia removed.
ceph;160649 said:I think the better question is why would it work slower in lower oxygen. When I hold my breath and swim under water, or when I scuba dive, I can get much farther and stay down longer if I'm relaxed. If I'm excited or trying to swim fast, my heart is going faster, my metabolic demands will be much higher. I may be more active but am using my air much less efficiently. I suspect the animal is regulating its activity levels to match the oxygen levels. An increase of the heart would increase demand for oxygen when there is less to be had - this could become a negative feedback loop.
But if you're at rest, and the room's oxygen drops, your breathing speeds up
CaptFish;160664 said:From my experience you will yawn a lot then just fall asleep. That's what happened to me.