Effects of alpha-blockade

You will be presented with responses to a dose of phenylephrine (30 nmole/kg), noradrenaline (10 nmole/kg) and vasopressin (40 nmole/kg). Tabulate the maximum changes in heart rate, systolic and diastolic blood pressure and in pulse pressure and the resting levels of these parameters.

Before proceeding further in this exercise, in the same table, make a note of your predictions as to the sort of modification in resting heart rate and mean blood pressure and in responses to the pressor agents which would be produced by prazosin.

You will then be presented with responses to a dose of prazosin (100 nmole/kg); note the effects. You will then be shown further responses to phenylephrine (30 nmole/kg), noradrenaline (10 nmole/kg) and vasopressin (40 nmole/kg).

Tabulate the maximum changes in heart rate, systolic and diastolic blood pressure and in pulse pressure for the remainder of the responses. Present the data in the form of a bar graph showing the size of the responses in mmHg.