title: Male and female rats express similar blood pressure responses to "push-pull" gravitational stress.
abstract: Brief exposure to -G(z) ("push") reduces eye-level blood pressure (elbp) during subsequent exposure to +G(z) ("pull"). This is called the "push-pull effect." To evaluate the influence of gender and the axis of rotation (pitch vs. roll) on the push-pull effect, 10 isoflurane-anesthetized male and 10 female Sprague-Dawley rats were restrained supine on a heated tilt board. Rats were subjected to two G profiles: a control profile consisting of rotation from 0 G(z) to 90 degrees head-up tilt (+1 G(z)) for 10 s and a push-pull profile consisting of rotation from 0 G(z) to 90 degrees head-down tilt (-1 G(z)) for 2 s immediately preceding 10 s of +1 G(z) stress. A total of 16 tilts consisting of equal numbers of control and push-pull trials and equal numbers of pitch and roll rotations were imposed by using a counterbalanced design. Gender exerted a significant effect on baseline (0 G(z)) ELBP (pressure was approximately 4 mmHg higher in females). In males and females, ELBP rose to a similar extent ( approximately 8 mmHg) during push, fell to a similar extent (approximately 18 mmHg) during control +G(z) stress, and fell to a similar extent (approximately 22 mmHg) during push-pull +G(z) stress. Altering the axis of rotation between the x-axis (roll) and the y-axis (pitch) did not influence the results. Thus males and females exhibit a push-pull effect; however, gender and axis of rotation do not appear to influence the push-pull effect in anesthetized rats subjected to tilting.
authors.affiliation: Department of Exercise Science, The University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Hakeman
authors.forename: Don D
authors.initials: DD
authors.lastname: Sheriff
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000778:Anesthetics, Dissociative / Q000494:pharmacology; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D018471:Hypergravity; D018472:Hypogravity; D007024:Hypotension, Orthostatic / Q000503:physiopathology; D007530:Isoflurane / Q000494:pharmacology; D007649:Ketamine / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012737:Sex Factors; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology; D014991:Xylazine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000778:Anesthetics, Dissociative; D018685:Anesthetics, Inhalation; D014991:Xylazine; D007649:Ketamine; D007530:Isoflurane