Trigeminal and chemoreceptor contributions to bradycardia during voluntary dives in rats

McCulloch, Paul F.; Ollenberger, Glenn P.; Bekar, Lütfü; West, Nigel H.

doi:10.1152/ajpregu.1997.273.2.r814

Cited by 18 publications

(17 citation statements)

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“…We show a dramatic bradycardia, a slight increase in MABP, and an increase in PP in laboratory rats during voluntary submergence. The 79% drop in HR, 11% increase of MABP, and 81% increase in PP in voluntarily diving rats during underwater submersion here is comparable to that seen by others (49,56,98). Cardiac output decreases in proportion to the bradycardia, and MABP is maintained near predive values because of the large increase in peripheral resistance throughout the dive (49,56).…”

Section: Discussionsupporting

confidence: 86%

The rat: a laboratory model for studies of the diving response

Panneton

Gan

Juric

2010

Journal of Applied Physiology

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Underwater submersion in mammals induces apnea, parasympathetically mediated bradycardia, and sympathetically mediated peripheral vasoconstriction. These effects are collectively termed the diving response, potentially the most powerful autonomic reflex known. Although these physiological responses are directed by neurons in the brain, study of neural control of the diving response has been hampered since 1) it is difficult to study the brains of animals while they are underwater, 2) feral marine mammals are usually large and have brains of variable size, and 3) there are but few references on the brains of naturally diving species. Similar responses are elicited in anesthetized rodents after stimulation of their nasal mucosa, but this nasopharyngeal reflex has not been compared directly with natural diving behavior in the rat. In the present study, we compared hemodynamic responses elicited in awake rats during volitional underwater submersion with those of rats swimming on the water's surface, rats involuntarily submerged, and rats either anesthetized or decerebrate and stimulated nasally with ammonia vapors. We show that the hemodynamic changes to voluntary diving in the rat are similar to those of naturally diving marine mammals. We also show that the responses of voluntary diving rats are 1) significantly different from those seen during swimming, 2) generally similar to those elicited in trained rats involuntarily "dunked" underwater, and 3) generally different from those seen from dunking naive rats underwater. Nasal stimulation of anesthetized rats differed most from the hemodynamic variables of rats trained to dive voluntarily. We propose that the rat trained to dive underwater is an excellent laboratory model to study neural control of the mammalian diving response, and also suggest that some investigations may be done with nasal stimulation of decerebrate preparations to decipher such control.

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Section: Discussionsupporting

confidence: 86%

The rat: a laboratory model for studies of the diving response

Panneton

Gan

Juric

2010

Journal of Applied Physiology

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“…Arrhythmia during expiration attempts during apnoea can also be seen in conscious sleeping dogs (Schneider et al 2000). The response observed by us during apnoea resembles that seen in diving rats (McCulloch et al 1997). This response may help reduce cardiac oxygen demand, improve myocardial perfusion and prevent cardiac necrosis, which can be induced by repetitive apnoeas (Simpson et al 2008).…”

Section: G H M Schoorlemmer and Otherssupporting

confidence: 62%

“…The tracheal incision was so small that no fixing of the implant was needed. The open end of the catheter was led subcutaneously to the area between the shoulder blades, where it was connected to an L-shaped hypodermic stainless-steel tube that exited through the skin (McCulloch et al 1997). The metal connector was closed with a plastic cap.…”

Section: Tracheal Balloonsmentioning

confidence: 99%

A new method to produce obstructive sleep apnoea in conscious unrestrained rats

Schoorlemmer¹,

Rossi²,

Tufik

et al. 2011

Experimental Physiology

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We developed a new method to produce obstructive apnoea in conscious rats. An inflatable balloon contained in a rigid Teflon tube was implanted in the trachea to allow the induction of apnoea without inducing pain. We also developed a balloon-tipped catheter that was advanced along the trachea into the mediastinum for the measurement of intrathoracic pressure. Rats recovered well from implantation of these balloons. The tracheal implant, while deflated, did not significantly impair normal breathing (thoracic pressure swing during rest was 4.5 ± 0.4 mmHg before implantation and 5.8 ± 0.5 mmHg 4 weeks after implantation; P > 0.2; n = 7). Apnoeas of up to 16 s could be made during rapid eye movement sleep without awakening the rat. During 15 s of balloon inflation, arterial O 2 saturation fell from 98 ± 0 to 80 ± 2% and partial pressure of CO 2 increased from 35 ± 1 to 44 ± 1 mmHg (n = 9; P < 0.001). Intrathoracic pressure changes during the respiratory cycle increased from 6.3 ± 0.2 to 38.5 ± 6.0 mmHg (P < 0.001; n = 4), indicating increased breathing effort. Heart rate fell from 373 ± 23 to 141 ± 18 beats min −1 (P < 0.001; n = 4), and the heart beat became irregular, with few beats during expiratory effort. These responses remained intact after 60 apnoea episodes. Responses developed slightly more slowly when apnoea started at the end than at the beginning of the respiratory cycle. As these balloons last for a long time, cause few complications, allow induction of apnoea during sleep, allow induction of apnoeas that start at a fixed point in the respiratory cycle and elicit cardiorespiratory responses similar to those observed in humans, these balloons may aid investigation of both acute apnoea and chronic intermittent sleep apnoea.

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“…The cardiovascular responses from swimming, voluntary diving and forced diving rats have been recorded using implanted telemetry devices (Figure 3; 8, [17][18][19][20] ) and trailing cannulae (Figure 4; [21][22][23] ). Immediately upon voluntary submersion, and within a single beat, heart rate decreases by 78% and mean arterial blood pressure decreases by 25% 17 .…”

mentioning

confidence: 99%

“…Trailing cannulae have also been used to show that rats ignore increasing arterial hypoxemia and hypercapnia while they are submerged 18 , and that pre-existing chemoreceptor drive does not have any effect on the cardiovascular responses to voluntary diving 21 .…”

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confidence: 99%

Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response

McCulloch

2014

JoVE

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Underwater submergence produces autonomic changes that are observed in virtually all diving animals. This reflexly-induced response consists of apnea, a parasympathetically-induced bradycardia and a sympathetically-induced alteration of vascular resistance that maintains blood flow to the heart, brain and exercising muscles. While many of the metabolic and cardiorespiratory aspects of the diving response have been studied in marine animals, investigations of the central integrative aspects of this brainstem reflex have been relatively lacking. Because the physiology and neuroanatomy of the rat are well characterized, the rat can be used to help ascertain the central pathways of the mammalian diving response. Detailed instructions are provided on how to train rats to swim and voluntarily dive underwater through a 5 m long Plexiglas maze. Considerations regarding tank design and procedure room requirements are also given. The behavioral training is conducted in such a way as to reduce the stressfulness that could otherwise be associated with forced underwater submergence, thus minimizing activation of central stress pathways. The training procedures are not technically difficult, but they can be time-consuming. Since behavioral training of animals can only provide a model to be used with other experimental techniques, examples of how voluntarily diving rats have been used in conjunction with other physiological and neuroanatomical research techniques, and how the basic training procedures may need to be modified to accommodate these techniques, are also provided. These experiments show that voluntarily diving rats exhibit the same cardiorespiratory changes typically seen in other diving animals. The ease with which rats can be trained to voluntarily dive underwater, and the already available data from rats collected in other neurophysiological studies, makes voluntarily diving rats a good behavioral model to be used in studies investigating the central aspects of the mammalian diving response. Video LinkThe video component of this article can be found at

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Trigeminal and chemoreceptor contributions to bradycardia during voluntary dives in rats

Cited by 18 publications

References 0 publications

The rat: a laboratory model for studies of the diving response

The rat: a laboratory model for studies of the diving response

A new method to produce obstructive sleep apnoea in conscious unrestrained rats

Training Rats to Voluntarily Dive Underwater: Investigations of the Mammalian Diving Response

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