Lecture 25: Hypertension Flashcards
What is respiratory activity correlated with?
sympathetic activity
What is sympathetic activity and heart rate modulated by?
respiration
What is altered respiratory sympathetic interaction a driver of?
the development of hypertension
When is co-transmission increased?
with irregular bursts of sympathetic activity (programs rat to become hypertensive)
How is sympathetic activity related to respiration?
phase-locked with respiration
In spontaneously hypertensive animals, sympathetic activity shows greater time-locked activity with respiration. What does this result in?
increased noradrenaline release from postganglionic sympathetic neurons
increased NPY co-transmission in postganglionic sympathetic neurons
What are the three classes of motor neurons that drive respiratory muscles?
thoracic, abdominal and phrenic motor neurons
Where in the spinal cord is the phrenic motor nucleus located?
C3-C5
Where in the spinal cord are the intercostal motor neurons located?
T1-L1
Where in the spinal cord are the abdominal motor neurons located?
T7-L1
Which structures prevent breathing in of too much air?
stretch receptors which increase in activity as lung volume increases
send information via the nucleus of the solitary tract and inhibit inspiratory motor neurons leading to expiration
Which group of neurons are located near nuclei involved in generating respiratory rhythm? What is their role?
rostral ventral lateral medulla
generate sympathetic activity to the vascular system
What are rRVLM neurons modulated by?
the respiratory system
What does contraction of the diaphragm produce?
increased venous return, reduced intrathoracic pressure and increased heart rate
Because respiratory modulation of sympathetic activity continues in the absence of lungs and changes in intrathoracic pressure, what can we deduce?
the neurons that drive respiratory and sympathetic activity must be interacting
What type of neurons are C1 neurons?
catecholaminergic
What type of neurons are non-C1 neurons?
unsure
What do C1 and non-C1 neurons contribute to?
the sympathetic activity that constricts blood vessels
Sympathetic activity is time-locked with ___, particularly in ___ rats. The resulting ___ of activity result in increased ___ release and ___ in postganglionic sympathetic neurons.
respiration, hypertensive, bursts, noradrenaline, NPY co-transmission
Where are C1 neurons located and what are they essential for?
located in the RVLM and are essential for respiratory-linked sympathetic activity
What does deletion of C1 neurons in spontaneously hypertensive rats result in?
decreased blood pressure
Why is it believed that C1 neurons are responsible for driving the development of hypertension?
enhanced sympathetic respiratory coupling is present in subjects who show an exaggerated BP response to moderate exercise
C1 neurons are responsible for sympathetic respiratory coupling
the number of C1 neurons in the brains of experimental animals is correlated with their BP
